Hydrazine-type monopropellant propulsion is well suited to attitude and orbit control systems on satellites. These systems are powered by micro thrusters with 30-40 wt.% iridium supported on alumina as catalyst for hydrazine decomposition. Carbon nanofibers with macroscopic shaping can be used as an alternative to the traditional support. This new material is prepared by chemical vapor deposition of ethane. on nickel particles dispersed upon the surface of the graphite felt. The carbon nanofiber-based composite was impregnated with 30 wt.% of iridium. The, overall performances of these catalysts have been evaluated for the hydrazine catalytic decomposition reaction in a 2N micro thruster into a vacuum chamber, i.e., under near actual flight conditions. The results obtained were compared with those of a commercial catalyst (Shell 405). The carbon nanofibers-based catalysts showed far better performance than the commercial catalyst from a standpoint of activity due, to its texture and its high thermal conductivity. (C) 2004 Elsevier B.V. All rights reserved.