Electrochemical splitting of water provides an attractive way to produce hydrogen fuel. Unfortunately, the efficient and large-scale H2 production is still hindered by the sluggish kinetics of the oxygen evolution reaction (OER) at the anode side of a water electrolyzer. Starting from metal-organic frameworks (MOFs), we demonstrate a template-engaged strategy to transform Ni-Ni Prussian blue analogue (PBA) nanoplates into porous carbon coated nickel phosphides nanoplates with mixed phases of Ni5P4 and Ni2P. For comparison, NiO and Ni(OH)2 porous nanoplates with the similar morphology have also been synthesized from the same precursor. Benefitting from their structural merits and the in situ formed catalytically active oxidized nickel species, the as-derived nickel phosphides manifest excellent electrocatalytic activity for OER superior to NiO and Ni(OH)2.