Micro-resistojets offer the best combination of simplicity, performance, wet system mass and power consumption for small satellites (<100kg, <50Watts) requiring mN level propulsion and low to moderate deltaV(<500m/sec). Classical competing devices such as cold gas thrusters have low performance, while liquid bipropellants have both high losses in the mN thrust range and are more complex. The advanced EP devices such as colloid thrusters are suitable for sub-mN thrust while electrostatic or electromagnetic thrusters are suitable for large deltaV missions where their higher dry mass is offset by higher specific impulse. Busek therefore proposes to develop a complete micro-resistojet system operating on ammonia or methanol delivering thrust up to 5mN, specific impulse approaching 300sec, impulse bit smaller than 1mNsec and power consumption lower than approximately 10Watts. Ammonia was chosen because it is less toxic than hydrazine while offering similar performance. Methanol is non toxic, greatly simplifying s/c fueling which is especially important for low cost missions. In Phase 1, breadboard system will be constructed and tested on our Maglev thrust stand that can resolve microNewton forces. In Phase 2 an Engineering Model of the system will be developed.