We demonstrate improved efficiency for the photocatalytic water splitting reduction half reaction by employing Au–Pt bimetallic cocatalysts. We employed nanoparticle-based photocatalysts consisting of CdSe@CdS rods tipped with Au, Pt, Au–Pt core–shell or Au decorated with Pt islands. By tailoring the composition and morphology of the Au–Pt bimetallic catalysts, we achieved more than a fourfold increase in activity for hydrogen production compared to pure Pt.