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Test Chamber Walkthrough

By ScotUpdated

Tactical Quick Answer

Portal has 20 test chambers numbered 00 through 19, followed by a four-part escape sequence through the maintenance areas and the GLaDOS boss fight. The chambers are grouped by the mechanics they teach: cubes and buttons from Chamber 00, the High Energy Pellet in 06, the scaffold in 07, goo in 08, the Emancipation Grill in 09, flinging in 10, the full portal device in 11, the double fling in 15, turrets in 16, and the Companion Cube in 17.

Portal has 20 test chambers (numbered 00 through 19) followed by an escape sequence and a boss fight. The chambers are grouped by the mechanics they teach. This walkthrough covers every puzzle solution, grouped by difficulty phase.

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If this is your first playthrough, try each chamber yourself before reading the solution. The puzzles are designed to be solvable through observation, and the satisfaction of figuring them out is the best part of the game.

Phase 1: Learning Portals (Chambers 0 to 7)​

These chambers teach you what portals do. You start with no tools and gradually gain the portal gun.

Chamber 00​

You wake up in a relaxation vault behind glass. A portal opens on the wall and you walk through it. This is not a pure walk-through tutorial though: Chamber 00 also introduces the Weighted Storage Cube, the Heavy Duty Super-Colliding Super Button, and the Emancipation Grill. You have to put a cube on the button to finish it.

Chamber 01​

Jump down into the pit. Static portals cycle to show you the cube, then the button, then the exit, and you carry the cube to the button. Valve's commentary notes that this chamber requires walking through a minimum of five portals in a specific order, which is the real lesson.

Chamber 02​

You watch a spawner create a blue portal, go through it, and drop into the pit, where the Handheld Portal Device sits on a central pedestal. This restricted version fires only blue portals, and the facility places the orange ones. Fire a portal to get yourself back out of the pit.

Chamber 03​

The lesson here is that orange portals are not exit-only. Up to now the facility's orange portals have only ever spat you out. This chamber forces you to walk into one.

Chamber 04​

Combines portal placement with the Weighted Storage Cube you already met in Chamber 00. The solve is to place a portal underneath a cube sitting in a pit so it drops through to you.

Chamber 05​

Two cubes and two buttons. You retrieve the first through a floor portal placed in a pit, then find the second and hold both buttons down.

Chamber 06​

Introduces the High Energy Pellet and non-portalable surfaces. There are no cubes in this chamber at all. An emitter fires a pellet that bounces around the room, and a receptor needs it to power the exit.

warning

The pellet kills you on contact. Do not stand in its path while setting up your portals. Watch its bounce pattern first, then place portals between bounces.

Chamber 07​

Introduces the Unstationary Scaffold, the moving platform on a track.

Phase 2: Momentum and Complexity (Chambers 8 to 14)​

These chambers introduce goo, the Emancipation Grill, and momentum.

Chamber 08​

Introduces Toxic Goo, and combines the pellet and the scaffold you learned in the previous two chambers.

Chamber 09​

Introduces the Emancipation Grill as a puzzle obstacle and not just a chamber exit. This is a cube and button puzzle, and it is where you first shoot a portal through a square opening in a wall.

Chamber 10​

This is where flinging is introduced, and it is the whole point of the chamber. Place a portal on the floor of a pit and another on a wall, drop in, and launch out sideways. The chamber lists no hazards at all, so you are free to experiment. It is also where the old Portal demo ended.

Chamber 11​

You receive the full portal device partway through, and both colors come under your control. Do not expect a gentle single-idea chamber though. Most of Chamber 11 is played before you reach the upgrade pedestal, and it involves a scaffold, a High Energy Pellet, retractable pedestal buttons, and goo.

This is where the game opens up. Every puzzle from here forward assumes you control both portals.

Chamber 12​

A fling refresher now that you control both portals yourself.

Chamber 13​

An Energy Pellet routing puzzle feeding into a cube and button section.

This is the first chamber available as an Advanced Map and a Challenge Map. Valve's commentary explains why: "This is the first map in which we experimented with solving the puzzle in as few portal placements as possible... we added the concept to a series of post-game Challenge maps."

Chamber 14​

A hall with stairs, moving platforms, a High Energy Pellet, goo, and a Victory Lift. The core of it is a cube up high and a button down low.

Phase 3: Hazards and Turrets (Chambers 15 to 18)​

The difficulty ramps up. Turrets appear, chambers get larger, and the puzzles combine multiple mechanics.

Chamber 15​

The double fling chamber, and the first place the game requires that maneuver. It also contains a pellet puzzle, an Emancipation Grill, timed switches, and a scaffold.

Solution: the double fling reuses the same pair of portals. You fall through them twice, gaining speed on each pass, instead of swapping a portal in mid-air between two separate pits.

  1. Set up a floor portal and a wall portal so that flinging out of the wall drops you back toward the floor portal.
  2. Fall in. You come out of the wall portal, arc across, and fall back into the floor portal at higher speed.
  3. The second exit carries enough momentum to reach the platform you could not otherwise get to.
tip

Portals can only be placed in the top half of the pellet room. Valve restricted the lower surfaces deliberately, so if you cannot get a portal to stick where you expect, that is why, and not a mistake on your part.

Chamber 16​

Your first turret encounter, and there are far more of them than one corridor's worth. Expect roughly a dozen separate turret take-downs across the chamber.

Approach:

  1. The two Weighted Storage Cubes are the point, not an optional aid. Use them as bulletproof cover to advance, and drop them on turrets to knock them over.
  2. Place a portal behind a turret group and tip them from behind.
  3. Alternatively, place a portal on the floor beneath a turret so it falls through and lands disabled.
  4. Work through the whole chamber instead of clearing one group and heading for the exit.

This chamber also contains the first Rat Man den, behind a wall panel.

Chamber 17​

The Companion Cube chamber. There are no turrets here. Its hazards are the High Energy Pellet, the Cube, and the incinerator.

Key steps:

  1. Grab the Companion Cube from the dropper.
  2. Use it on buttons to open your way forward.
  3. Carry the Cube in front of you as a shield against the High Energy Pellet. Valve's commentary notes that many playtesters misread this hall as an avoid-the-ball timing puzzle when it was designed as a shielding puzzle.
  4. Cross the section of three lifts by jumping between them. There is no pellet-activated elevator.
  5. At the end of the chamber, GLaDOS tells you to incinerate the Cube. Drop it in and the exit opens.

The second Rat Man den is in this chamber.

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You cannot skip the incineration. The door does not open until the Companion Cube is destroyed. GLaDOS comments on how quickly you did it.

Chamber 18​

Multiple levels, pellets, a scaffold, flinging, and four turrets in an open second section and not a corridor.

Key sections:

  1. The turrets. The intended solution is to route the High Energy Pellet into each turret, timed against the emitter's firing cycle. Portalling behind them is not the designed approach here.
  2. Pellet puzzle. Route the pellet through portal redirections into the receptor.
  3. Platform section. The activated receptor powers a moving platform.
  4. Final fling. A momentum fling to reach the exit.

Chamber 19 and the Escape​

Chamber 19​

The final "test." A scaffold carries you toward an incinerator while GLaDOS congratulates you: "The test is now over... All Aperture technologies remain safely operational up to 4000 degrees Kelvin... Thank you for participating. Goodbye."

You are not supposed to comply.

Escape the furnace:

  1. As the scaffold nears the incinerator, fire a portal onto the far wall, aiming above the handrails so nothing blocks the shot.
  2. Place your second portal on a reachable surface and step through before the platform tips you in.
  3. You are now behind the scenes in Aperture Science's maintenance areas.
note

The famous "assume the party escort submission position" line does not play here. GLaDOS only says it after you escape, once she has started trying to talk you back in.

The Escape Sequence​

The maintenance areas are a sharp contrast to the clean test chambers. Rusty pipes, abandoned offices, concrete corridors. No more chamber numbers. GLaDOS is aware you escaped and alternates between threatening you and trying to lure you back.

What to expect:

  • The walls are mostly concrete and accept portals, but not all surfaces work. Valve's commentary is explicit that teaching you which new surfaces take portals is part of the point of this section.
  • The escape runs across four separate levels. Parts 1 and 2 are the piston and goo sections, and Parts 3 and 4 are where the turrets live, with Part 4 built around a large turret ambush.
  • Hidden rooms contain graffiti from a previous occupant. "The cake is a lie" appears here as well as in Chamber 16.
tip

Look for Rat Man dens, but do not wait until the escape to start. There are six in the game and the first three are back in Test Chambers 16, 17 and 18, behind wall panels. The remaining three are in Chamber 19. If you only search the maintenance areas you will miss all of them.

The GLaDOS Boss Fight​

You reach GLaDOS in her central chamber. She is a massive AI unit suspended from the ceiling. A rocket turret is mounted on the wall.

How to win:

  1. The first core falls off on its own. As GLaDOS is "deploying surprise in five, four", her Morality Core drops without any action from you. She asks, "Do you see that thing that fell out of me? What is that?" Do not stand around waiting for a rocket to dislodge it.
  2. Burn that core to start the fight properly. Only after you incinerate the first core does she begin flooding the chamber with neurotoxin.
  3. Redirect rockets through portals. GLaDOS hangs from the ceiling and the Rocket Turret sits at floor level, so there is no line between them to stand in. Put one portal on a ground-level wall in the rocket's path, and the other under one of the monitor screens facing GLaDOS. The rocket goes in low and comes out aimed at her.
  4. Stand still until the turret locks on, then step aside. The Rocket Turret slowly acquires you and emits a sound before firing a single rocket. You want it to commit to your position in front of your portal, then move.
  5. Each hit knocks off another core. Three of the four cores need a rocket, since the first came free.
  6. After the final core is destroyed, a portal malfunction tears the room apart and carries everything to the surface.

Getting a core into the incinerator:

You cannot simply carry a core in and drop it. The procedure is:

  1. Place a portal on the wall behind the incinerator.
  2. Set the core down on the floor.
  3. Walk to the small side room and press the pedestal switch to open the incinerator.
  4. Fire your other portal underneath the core so it falls through and out into the fire.
danger

The neurotoxin countdown runs six minutes, not five, and it starts only once you have burned the first core. GLaDOS never states a duration out loud. The clock you are watching is on the wall monitors in the chamber, so find one early. Her line about packing "as much living as you can into the next couple of minutes" comes after the second core and is a taunt, not a timer.

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No sentry turrets are deployed during this fight. GLaDOS's line about not being able to shut off "the turret defenses" refers to the single Rocket Turret. Redirecting a rocket back into that turret only fizzles, so do not spend time trying to destroy it.

After the Credits​

After defeating GLaDOS and watching the ending, the credits roll with the song "Still Alive."

  • Advanced Maps and Challenge Maps cover Test Chambers 13 through 18. These do not wait for the credits. Each one unlocks as soon as you complete the matching chamber during the campaign, so you can start them mid-playthrough.
  • Commentary Mode is the one that genuinely unlocks on completing the game. Replay with developer commentary nodes explaining the design decisions behind each chamber. Note that achievements do not unlock while commentary is active.

For a full guide to the post-game content, see Advanced Maps and Challenges.

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The 2007 ending already showed Chell lying outside among GLaDOS's remains before panning through a room full of cake. What Valve's March 3, 2010 patch added was the final beat, where an unseen Party Escort Bot drags her back inside. The Xbox 360 and PlayStation 3 releases never received that update and still end the original way.

Frequently Asked Questions​

How many test chambers are in Portal?

There are 20 test chambers, numbered 00 through 19. After Chamber 19 you get an escape sequence through the maintenance areas and then the GLaDOS boss fight.

How do you escape the furnace in Chamber 19?

As the platform carries you toward the fire pit, look to the side for a portalable wall. Place a portal there and another on any reachable surface behind you, then step through before the platform drops you into the fire.

How do you beat GLaDOS at the end of Portal?

Portals are mandatory, because GLaDOS hangs from the ceiling and the Rocket Turret sits at floor level, so you cannot line them up directly. Put one portal on a ground-level wall in the rocket's path and the other under a monitor screen facing GLaDOS. Stand still until the turret locks on, then step aside. The first of her four cores falls off on its own, so only three need a rocket.

How long is the neurotoxin timer in the GLaDOS fight?

Six minutes, and it only starts once you have incinerated the first core. GLaDOS never states the duration out loud, so watch the wall monitors in the chamber for the countdown.

How do you put a personality core in the incinerator?

You cannot carry it in. Place a portal on the wall behind the incinerator, set the core on the floor, go to the small side room and press the pedestal switch to open the incinerator, then fire your other portal underneath the core so it drops through.

Do you have to incinerate the Companion Cube in Chamber 17?

Yes. The exit door does not open until the Weighted Companion Cube is destroyed, so there is no way to skip it or carry the Cube forward.