Abstract Detoxification of water bodies from industrial pollutant dyes by semiconductor heterojunction composites briefed. Synthesis of ZnO/SnS core/shell nanocomposites by ecofriendly hydrothermal method presented. Characterization by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis absorption spectroscopy photoluminescence (PL) etc., were presented. Abundance of orthorhombic ZnO and hexagonal SnS was confirmed by X-ray diffraction. Compression of hexagonal ZnO planes (as core nanorods) and SnS core nanoparticles infers growth of core shell structure. Average crystallite size is found to be 5.8 nm. Structure and TEM morphology correlated. XPS reveals abundance of elemental oxidation state. Photocatalytic activity was studied by using visible light irradiation. Photoluminescence for ZnO/SnS core/shell nanocomposites inferred significant emission peaks. Enhanced PCA observed against visible light. Methylene blue dye characteristic PCAby its degradation evinced. PCA is found optimal for Z-S3. Configuration of bandgap promoted growth of novel hetero junction. Physical mechanism is proposed for the enhanced photocatalytic activity as accompanied by degradation of MB dye.