This paper presents the results of a program to describe the operational characteristics of an engineering model multipropellant resistojet for application as an auxiliary propulsion system for the space station. Performance was measured on hydrogen, helium, methane, water (steam), nitrogen, air, argon, and carbon dioxide. Thrust levels ranged from 109 to 355 mN, power levels ranged from 167 to 506 W, and specific impulse values ranged from 93 to 385 s, depending on the propellant, chamber pressure, and heater current level selected. Detailed thermal maps of the heater and heat exchanger also were obtained for operation with carbon dioxide.