Sodium borohydride, NaBH4, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). The hydrogen yield of sodium borohydride hydrolysis reaction was studied. The effect of temperature, NaBH4 concentration, NaOH concentration and catalyst type on the hydrogen yield from NaBH4 hydrolysis reaction were measured. The catalysts of Co-P/Cu, Co-B/Cu and Co-P-B/Cu were used in this study and there was no different effect of these catalysts on the hydrogen yield from NaBH4. Under the temperature of 60 ℃, the hydrogen yield decreased as NaBH4 concentration increased due to formation of gel with by-products and reactants. The gel formed during NaBH4 hydrolysis reaction diminished the hydrogen evolution rate and total volume of hydrogen. Addition of NaOH stabilizer enhanced the formation of gel and then decreased the hydrogen yield.