Novel organic-inorganic polyimide (PI)-Zn0.25Cd0.75S composites with high-efficiency visible light performance was prepared by a facile and template free hydrothermal method. The obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photo-electron spectroscopy (XPS), ultraviolet-visible diffuse reflection spectroscopy (DRS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD and SEM results revealed that the PI exhibited a high degree of polymerization. The DRS characterization showed that the light absorption exhibited regular shifts upon the change of PI/Zn0.25Cd0.75S mass ratio. The TEM results proved the in situ growth of finely distributed Zn0.25Cd0.75S nanoparticles on the surface of PI sheets. The as-prepared samples exhibited superior photocatalytic activity compared with PI and Zn0.25Cd0.75S toward the degradation of dyes under visible light irradiation. The electrochemical impedance spectroscopy (EIS) confirmed that the separation efficiency of electron-hole pairs was greatly improved for the formation of heterojunction. The activity enhancement of PI/Zn0.25Cd0.75S composites could be attributed to the interfacial electronic interaction and high migration efficiency of photo-induced carriers. A possible photodegradation mechanism was proposed for the degradation of dyes over PI/Zn0.25Cd0.75S composites. (C) 2015 Elsevier B.V. All rights reserved.