In this paper, nanostructured CoP with different morphologies, including nanowires, nanosheets and nanoparticles, were prepared through an organic solvent-free low-temperature phosphidation reaction under Ar. These nanostructures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller specific surface area measurements. We further studied their electrocatalytic properties towards the hydrogen evolution reaction in acidic media and found that CoP nanowires exhibited the highest catalytic activity and stability.