Abstract: A gas arrestor separates entrained gas from a liquid medium. The gas arrestor is a porous member, such as a woven mesh screen having pores of a size sufficiently small to enable liquid transport while inhibiting gas transport. Since the trapped gas has a tendency to accumulate on the porous member impeding continued liquid flow, a wick extends in an upstream direction from the porous member. When used in spacecraft to provide substantially gas-free liquid to a thruster, the gas arrestor is located between a tank of pressurized liquid propellant and a gas generator. Improved results are obtained by locating the gas arrestor between a pressure reducing liquid fluid resistor and the gas generator.