Chemical hydrides represent a class of promising hydrogen storage materials. Solid sodium borohydride in particular offers superior fuel stability and its reaction with acid provides a new approach for hydrogen generation. In this study, the chemistry involved in a hydrogen storage system based on solid NaBH4 and aqueous H2SO4 was studied experimentally. Factors influencing hydrogen generation dynamics, sodium borohydride conversion, and borax byproduct distributions were studied. A fuel-only energy density of 23 10 Wh/kg (on the basis of lower heating value of hydrogen contained) is projected for hydrogen storage using pure sodium borohydride and 31 wt% H2SO4.