|Rate of fire (maximum)||1 (1)|
|Reload speed (maximum)||3.5 (2.6)|
|Magazine (maximum)||1 (1)|
|Inventory size||6x2 (12)|
|Upgrades||1x Target-Leading System|
3x Reload Speed
The PAX-22 Tranquilizer Rifle is a non-lethal, silent weapon made by Military Arms of Ostrava (MAO) located in the Czech Republic. It was intentionally developed for capture operations on wildlife and other organic targets.
The PAX-22 is a one-shot weapon that uses break-action loading. The darts are propelled by compressed air from an HPA (High Pressure Air) tank located under the rifle's receiver. The PAX-22 features a scope similar to the crossbow.
Range: 45 meters.
It uses hypodermic darts manufactured by Kaiga Incorporated under the name of "hypo-dyne black". These are usually sold in packs of 5 darts. They consist of a mixture of different psychoactive drugs and anaesthetics such as diazepam, phencyclidine, ketamine and morphine.
The PAX-22 Tranquilizer Rifle is a long-range, single-shot nonlethal firearm that knocks individual targets unconscious. Upon firing, the PAX-22 fires tranquilizer darts that inject nonlethal sedatives into the target, and after several moments the organic enemy will be incapacitated. Headshots on vulnerable enemies will instantaneously knock out the target. Although fitted with a scope, the tranquilizer darts fired by the PAX-22 both drop and have a travel time. These factors must be considered when going for long-range takedowns.
The rifle occupies a 6x2 area in your inventory, and ammo is 1x2.
The PAX-22 is useful for both scouting over long distances and knocking out individual targets at long range, but can also be fired from cover at mid ranges. Due to the fact that unconscious enemies can be revived by their allies, thus raising the alert level to alarmed, the PAX-22 is best reserved for enemies that are either alone, or can be reached quickly by the player to hide their bodies.
The tranquilizer darts fired by this weapon require several seconds to take effect barring a headshot. Though a disadvantage in active combat situations, this can also be exploited by the player. A player may snipe a target at long range with this weapon, then reload in the time it takes for the tranquilizers to go into effect. When another enemy comes to investigate their fallen comrade, the player may snipe that target too. This tactic can be useful for incapacitating large numbers of enemies at very long range, provided the player is unseen and fast enough to shoot down all targets before they can be revived by their allies. Bear in mind, however, that on Give Me Deus Ex difficulty, even a headshot isn't always an instant knock-out. Some enemies, most notably "heavy" ones, will stay on their feet for a few more moments, although they still pass out quicker than after a non-headshot hit.
It can be very useful late in the game as some of the more armored enemies can be taken down with a single dart (excluding bosses) such as the Heavy Rifle equiped enemies found half way though the game.
It can pose a challenge for the Pacifist trophy:
- From time to time, a victim may be killed by the dart. However, it has been confirmed by multiple players that the trophy can still be obtained even if a target is shown as dead upon first examination, so long as the "Merciful Soul" XP bonus was obtained upon knocking the target out. 
- Moving an unconscious victim may kill it; that is, the status is "zzz" (unconscious), you move it, the status moves to "skull" (dead). This behavior is not restricted to the tranquilizer rifle, but also happen with take-downs and victims of the stun-gun .
The PAX-22 supports standard reload speed upgrades, along with the target-leading package, an active mod which alters the scope to provide an aiming point when active, allowing more effective targeting of moving enemies.
- The PAX-22 is mostly based on the Pneu-Dart (X-Caliber) Rifle, using the same reloading technique and has a lot of its design. The firing-loading mechanism may have also been inspired by the Thompson Arms Contender pistol/rifle.
- "PAX" translates into "peace" from Latin to English. The designation of the PAX-22 is fitting given its role in the Pacifist trophy/achievement.
- In the film, Serenity (Part of the Firefly series), a chemical named PAX-22 is introduced to the air supply of a terra formed planet in an attempt to calm the population.
- At the beginning of the first mission if you request a long-range non-lethal weapon from David Sarif.
- Grayson's shop.
- Inside a storage room in the southwest corner of the highest level of the Kuaigan district in Hengsha, near a gate to the Youzhao district.
- Lin Fu Ren's shop in the Hung Hua Hotel during the first visit to Hengsha.
- Locked (lvl 2) storage near the Hung Hua Hotel during the first visit to Hengsha. On the path to Youzhao district.
- Tai Yong Medical, as you're working your way up through the Pangu, inside a ventilation shaft, along with a corpse and weapon upgrade.
- Belltower dock In one of the security containers.
- Omega Ranch, in a weapon cabinet in room B-21 on the second floor of the Bio-Mech Lab.
- In The Missing Link DLC, on the Hei Zhen Zhu, in the last cargo hold before you climb up to the deck. Another one is located inside a shipping container as soon as you exit the Hai Zhen Zhu to Rifleman Bank Station. The shipping container is directly under the office, and requires the punch through wall upgrade to enter. If you forgot to pick up this critical weapon while on the Hei Zhen Zhu, this is your last chance to obtain it.