CdS encapsulated cubic MCM-48 mesoporous photocatalysts were prepared by a post-impregnation method. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption isotherm, UV-visible diffuse reflectance spectroscopy (DRS), FT-IR spectrometry, X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), and photoluminescence (PL) spectroscopy were employed for the characterization of the CdS incorporated MCM-48 siliceous materials. MCM-48 was loaded with different amounts of CdS. In the current study, all the samples showed photocatalytic activity under visible light (λ > 400 nm) irradiation for production of hydrogen from splitting of water in the absence of Pt, which is usually used in photocatalytic splitting of water. The photocatalytic activity of the CdS incorporated MCM-48 mesoporous photocatalysts was found to be dependent on the CdS loading and the pore size of MCM-48 siliceous support. The highest solar hydrogen evolution rate by visible light irradiation from the splitting of water was determined to be 1.81 mmol h⁻¹ g_CdS⁻¹ and the apparent quantum yield was estimated to be 16.6%.