Silicon micromachining is an attractive technique for batch production of a wide class of miniaturized components and systems. In particular, micromachined components can be combined with semiconductor lasers, microlenses, and micromechanics to develop a new class of instruments. A worldwide impulse in micromachining is originated by the space industry. Space exploration in the new millennium will mostly rely on drastically miniaturized spacecraft by today's standards. It is worth to note that the space community is used to speak about nanosatellites when satellite mass ranges between 1 and 10 kg, while microsatellites range between 10 and 100 kg (ESA/IPC 81 Information Note, Paris, October 2000). A key point for precise micronanosatellites orbit and attitude control is the development of a suitable propulsion system, weighting a few grams and capable of few muN of thrust. A microthruster complying these requirements is under development jointly by our laboratory and Mechatronic, using MEMS technology. The article will show the microthruster design, fabrication processes, and the experimental setup to test in space the micropropulsion system prototype. The experiment will be performed on-board the microsatellite UNISAT-2 of the University of Roma.