A high-performance bifunctional Co-P foam catalyst was successfully synthesized by facile one-step electrodeposition at a high cathodic current density. The synthetic approach includes fast generation of hydrogen bubbles as well as fast deposition of Co-P, which played a key role in forming a porous Co-P foam structure. The Co-P foam exhibits remarkable electrocatalytic activity and stability in both acidic and alkaline solution. Its HER activity was recorded with an over potential of 50 mV in 0.5 M H2SO4 and 131 mV in 1 M KOH at 10 mA cm(-2), which is comparable to that of commercial Pt/C (eta@10 mA cm(0.5 M H2SO4)(-2): 33 mV, (eta 10) (mA), (1M) (KOH): 80 mV). The Co-P foam (eta@10 mA cm(-2): 300 mV) exhibits better OER activities than Ir/C (n@10 mA cm(-2): 345 mV) and RuO2 (eta@10 mA cm(-2): 359 mV) in 1 M KOH solution. The excellent performance of the Co-P foam as an HER and OER catalyst can be attributed to the charge separation between Co and P in Co-P foam as well as the porous foam structure providing a large electrochemically active surface area (ECSA). The ECSA of the Co-P foam was calculated to be 118 cm(2), which was 2.4 times higher than that of a Co-P film (49 cm(2)).