Low-cost and highly active water oxidation electrocatalysts are increasingly demanded to improve the efficiency of water splitting. Herein, for the first time, we developed a facile strategy to design a three-dimensional flower-like cobalt nickel phosphate as such an electrocatalyst. The cobalt nickel phosphate was directly supported on Ni foam ((Co0.5Ni0.5)(3)(PO4)(2)/Ni) via a simple two-step hydrothermal method. This method offers several advantages including low cost, facile synthesis and binder-free. Benefiting from its three-dimensional flower-like nanostructure with a big specific surface, high conductivity and the synergic effect of metal ions are the as-synthesized (Co0.5Ni0.5)(3)(PO4)(2)/Ni reveals excellent oxygen evolution reaction activity in alkaline electrolyte. It exhibits a low overpotential of 273 mV to reach a current density of 10 mA cm(-2) and a Tafel slope of 59.3 mV dec(-1) in 1.0 mol L-1 KOH. Notably, the (Co0.5Ni0.5)(3)(PO4)(2)/Ni also operates efficiently in 30 wt% KOH, capable of affording an anodic current of 10 mA cm(-2) at a lower overpotential of 246 mV and retains its catalytic performance for at least 30 h.