A Cadmium sulfide/ multi-walled carbon nanotubes/polymer nanocomposite (CdS/MWCNTs/polymer) was fabricated via a facile precipitation process by depositing nanocrystalline CdS on carbon nanotubes/crosslinked chitosan nanocomposite films and  characterized by X-ray diffration (XRD). Under simulated solar light irradiation, a combination of CdS/MWCNTs/polymer and H₂O₂ (1.0 mM) was found to be highly efficient for photocatalytic decolorization of a soluble azo dye, methyl orange (MO), even at neutral pH values. 99.9 % of methyl orange solution was successfully decolorized after 90 min under simulated solar light irradiation with15 mg L^-1 of initial MO concentration, 1.0 mM of H₂O₂ concentration and 0.70 g L^-1 of photocatalyst dosage. Experimental results also indicated that the phtocatalytic decolorization of methyl orange solution was strongly influenced by parameters such as photocatalyst dosage, H₂O₂ concentration, pH and initial dye concentration and followed a simplified Langmuir–Hinshelwood (L-H) kinetic model with high R² values.. The fact that 88.1 % of initial decolorization was kept after five cycles indicated that the process was repeatable. As a result, the CdS/MWCNTs/polymer-H₂O₂ will potentially provide cheaper and cleaner means for the effective treatment of dyeing effluents since it increased substantially the efficiency of dye decolorization and could take full advantage of economical solar light.