Solar photocatalytic water splitting for the production of hydrogen has been a core aspect for decades. A highly active and durable photocatalyst is crucial for the success of the renewable hydrogen economy. To date, the development of highly effective photocatalysts has been seen by the contemporary research community as a grand challenge. Thus, herein we put forward a sincere attempt to use a Pt-Ni x alloy nanoparticle (NP) cocatalyst loaded CdS photocatalyst ((Pt-Ni x )/CdS) for photocatalytic hydrogen production under visible light. The Pt-Ni x alloy NP cocatalyst was synthesized using a one-pot solvothermal method. The cocatalyst nanoparticles were deposited onto the surface of CdS, forming a Pt-Ni x /CdS photocatalyst. Photocatalytic hydrogen production was carried out using a 300 W Xe light equipped with a 420 nm cut-off filter. The H 2 evolution rate of the Pt-Ni 3 /CdS photocatalyst can reach a value as high as 48.96 mmol h -1 g -1 catalyst, with a quantum efficiency of 44.0% at 420 nm. The experimental results indicate that this Pt-Ni 3 /CdS photocatalyst is a prospective candidate for solar hydrogen generation from water-splitting.