NaB3H8 has advantages over NaBH4 and NH3BH3, two most widely studied chemical hydrides for hydrogen storage via hydrolysis. NaB3H8 has an extraordinary high solubility in water and thus possesses a high theoretical capacity of 10.5 wt% H via hydrolysis, in contrast to 7.5 wt% for NaBH4 and 5.1 wt% for NH3BH3. NaB3H8 is reasonably stable in water which makes it unnecessary to add corrosive NaOH as a stabilizer as the case for NaBH4. Furthermore, hydrolysis of NaB3H8 can be catalyzed by a Co-based catalyst with fast kinetics that is comparable to Ru-based catalysts. Therefore, cost-effective hydrolysis of NaB3H8 is possible for practical applications. A high capacity of 7.4 wt% H was achieved when water was included in the materials weight.