How do small thrusters utilizing monopropellants like Hydrazine generate hot gas reliably without an oxidizer?

The single chemical decomposes exothermically when passed over a catalyst bed

Monopropellants are distinct because they function without needing a separate oxidizer component; they are self-contained chemical systems. A classic example is Hydrazine, which, when passed over a specific catalyst bed within the thruster assembly, undergoes rapid, controlled decomposition. This decomposition process is exothermic, meaning it releases significant heat, generating a large volume of hot gas necessary for providing thrust for fine control maneuvers like attitude adjustment. This mechanism provides extremely high reliability for small systems that must fire precisely, as it eliminates the complexity and potential failure points associated with managing two separate fluid flows characteristic of bipropellant engines.