Abstract: A catalyst for initiating the spontaneous decomposition of hydrazine and hydrazine nitrate into ammonia, nitrogen and hydrogen comprises ruthenium supported on high-surface area silica, alumina or silica-alumina substrates promoted with oxides of alkalis, alkaline earths, transition elements and rare earths. The catalyst is particularly useful in monopropellant rocket engines and gas generators and is characterized by: high activity when used in either a pulsed or continuous mode, minimal loss in crush strength or surface area after firing and use of non-strategic materials.