A new fast combustion inflator based on the reactions of methane-oxygen mixtures has been developed. The performance of this inflator was evaluated in terms of pressure-time relationships inside the inflator and in a receiving tank simulating an air bag and by assessing the temperature-time relationship in the tank. In order to develop this inflator, several critical issues were studied, including stoichiometry, initial mixture pressure and extreme ambient conditions. Other design parameters such as burst disk thickness and type, ignition device, tank purging gas, concentration of carbon monoxide, severity of temperature in the tank, and the inflator size were investigated and optimized. To simulate the behavior of this inflator, a theoretical and integrated model was developed. The experimental results made at different conditions were found to be in agreement with the model. The performance of this inflator was compared with that of sodium azide and strategies for its implementation in an actual air bag system were formulated.