Improving the catalysts of the hydrogen oxidation reaction (HOR) in alkaline conditions is necessary for developing anion exchange membrane fuel cells as alternatives to conventional proton-exchange-membrane fuel cells. Previous studies have demonstrated Pt catalyst improvement by forming coordinatively saturated surface sites (i.e., plane surfaces) as well as by combining Pt with other metals. In this study, Pt–Ni thin-film catalysts, which exhibited an enhanced activity compared to Pt monometal thin-film and nanoparticle catalysts, were prepared by a pulsed arc plasma method. Additionally, the prepared catalysts were heated to form Pt–Ni alloy catalysts with further improved activity. Thus, Pt–Ni alloy thin films were demonstrated as highly active structures in an alkaline HOR.