A cold gas thruster is a type of propulsion system which uses the expansion of pressurized gas to generate thrust. It consist of a fuel tank, a regulating valve, and a propelling nozzle. The nozzle of a cold gas thruster is generally made of a convergent-divergent shape so that it provides a required thrust in flight. The nozzle is shaped in such a manner that the high-pressure, low-velocity gas that enters the nozzle is expanded as it approaches the throat (the narrowest part of the nozzle) of the nozzle, where the gas velocity matches the speed of sound.

The propellant used in a cold gas thruster can be a solid, liquid, or gaseous propellant. Typically, an inert pressurized gas is used for generating thrust, or propellant with a high specific impulse is chosen since a higher specific impulse indicates better performance by the thruster.

The main advantage of a cold gas thruster is the lack of combustion taking place and hence as a result, it eliminates the need for heat management systems. Cold gas thruster is smaller compared to traditional thrusters, which makes it a suitable choice for missions with limited volume and weight requirements. The inert fuel used by cold gas thruster is inexpensive but has lower thrust and efficiency compared to monopropellant and bipropellant thrusters.

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