Unsupported and Al2O3-supported molybdenum phosphides (MoP) were tested as catalysts for the decomposition of hydrazine (N2H4), in comparison with previously studied Mo2N catalysts. The results showed that the activity increased with MOP loading on the MoP/Al2O3 catalysts and that the supported MOP catalysts were more stable during hydrazine decomposition compared with the supported Mo2N catalysts. FTIR results indicated that N2H4 decomposed on the Mo sites on the MoP, similar to the case of Mo2N. FTIR and microcalorimetric adsorption measurements showed that NH3 was adsorbed only moderately on the MOP catalyst, giving it better catalytic stability than the Mo2N, for which strong adsorption of NH3 blocked the active sites and led to a sharp decrease in activity. (c) 2007 Elsevier Inc. All rights reserved.