<p>This study developed a novel CdS-based photocatalyst by employing a Cd-MOF precursor and integrating CoMoS₄ as a transition bimetallic cocatalyst by two-step hydrothermal method. CdS was initially obtained by converting Cd-MOF through a sulfidation process, followed by the controlled incorporation of CoMoS₄ at varying molar ratios (2.5%, 5%, and 10%). Structural and morphological analyses (SEM-EDS, XRD, FT-IR) confirmed the transformation of Cd-MOF to crystalline CdS and the successful formation of CoMoS₄/CdS heterojunctions. The incorporation of 2.5% CoMoS₄ significantly increased the BET surface area. UV–vis diffuse reflectance spectroscopy revealed a red-shifted absorption edge and a narrowed band gap of 2.26&#xa0;eV for the 2.5% CoMoS₄/CdS composite. Photoluminescence (PL) quenching and XPS analysis indicated improved charge separation and strong interfacial bonding. Mott–Schottky (M-S) measurements revealed conduction band potentials for CdS and CoMoS₄, supporting the proposed heterojunction mechanism. Among the synthesized composites, the 2.5% CoMoS₄/CdS catalyst exhibited the highest photocatalytic hydrogen production rate of 5.8 mmol/g·h under visible light, representing a tenfold increase compared to bare CdS (0.52 mmol/g·h). These findings demonstrate that CoMoS₄ is an effective cocatalyst for enhancing hydrogen generation through improved light harvesting and charge-carrier separation, offering a promising strategy for solar-to-hydrogen energy conversion.</p> Graphical Abstract <p></p>