A highly active cobalt-iron-phosphorus catalyst was fabricated to generate hydrogen from the hydrolysis of NH3BH3 by facile one-step electrodeposition method. The performance of the catalyst was optimized by electrodeposition condition via controlling microstructure and composition. As the applied cathodic current density was increased from 10 to 400mA/cm(2), the particle sizes of the Co-Fe-P catalysts increased from 1 to 15 mu m. With the increase in a deposition time, the particles of the Co-Fe-P catalyst became densely agglomerated. The Co-Fe-P catalyst deposited at 50 mA/cm(2) for 5min, which had a particle size of 2 mu m, exhibited the best hydrogen generation rate of 2858 ml min(-1)g(-1)-catalyst in 1 wt% NH3BH3 solution at 30 degrees C. With an increase in the solution temperature from 10 to 60 degrees C, the hydrogen generation rate increased exponentially from 1543 to 8915 ml min(-1)g(-1)-catalyst in the 1 wt% NH3BH3 solution. The activation energy for the hydrolysis of NH3BH3 by the Co-Fe-P catalyst was calculated and found to be approximately 25 +/- 3 kJ/mol, which is comparable to those of noble metal-based catalysts. Furthermore, with an increase in the concentration of NH3BH3 from 0.5 wt% to 3 wt%, the hydrogen generation rate of the Co-Fe-P catalyst increased gradually from 1900 ml min(-1)g(-1)-catalyst to 8105 ml min(-1)g(-1)-catalyst at 30 degrees C.