A nitrocellulose-free, gas-generating composition for use in vehicle occupant restraint systems, in particular in a belt tensioner gas generator, substantially consists of at least one nitrogen-containing organic fuel in a proportion of 55 to 70% by weight, an inorganic oxidator in a proportion of 30 to 45% by weight, at least one combustion moderator in a proportion of up to 10% by weight and up to 5% by weight conventional adjuvants and additives, each in relation to the overall weight of the composition. The composition has a pressure exponent of less than 0.35 and a combustion rate at 200 bar of at least 40 mm/s.