A comprehensive report has been presented on the recent developments of CdS and its hybrid with focus on photo and electrocatalytic applications. CdS as semiconductor possess remarkable chemical stability for redox reactions, high absorption capacity, negative conduction bandedge, and offers diverse morphologies. Photo and electrocatalytic applications of CdS and its hybrids include low cost and green water-splitting for H-2 generation, wastewater treatment by degradation of organics toxins e.g., Cr (VI), Rhodamine B, Methylene blue (MB), Methyl orange etc., and fuel production such as CH4, Ethylene, Methanol, Ethanol, HCOOH, and CO via photocatalytic and electrocatalytic CO2 reduction. Starting from the fundamentals, design,synthesis process and catalytic activity factors of CdS-based catalysts for various applications are summarized.