Sodium borohydride, NaBH4, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). The durability of Co-P-B/Cu catalyst for sodium borohydride hydrolysis reaction was studied. The effect of reaction temperature, NaBH4 concentration, NaOH concentration and calcination temperature of catalyst on the durability of Co-P-B/Cu catalyst were measured. The gel formed during hydrolysis reaction affected the durability of catalyst (loss of catalyst). Formation of gel increased the loss of the catalyst. When NaBH4 concentration was high and reaction temperature was higher than 60 ℃, loss of catalyst was low because gel was not formed. But under the temperature of 40 ℃, loss of catalyst increased due to gel formation When NaBH4 concentration was 40 weight % and the reaction temperature was 40 ℃, the loss of catalyst increased as the NaOH concentration increased. As the calcination temperature of catalyst decreased, the loss of catalyst decreased and the activity of catalyst decreased. Calcination of the catalyst at high temperature enhanced the durability of catalyst but diminished the activity of catalyst.