The activity of hybrid nanostructured core-shell photocatalysts based on cadmium sulfide, titanium dioxide, and silicon dioxide has been investigated in the partial oxidation of ethanol under irradiation with visible light. The SiO2/CdS and TiO2/CdS photocatalysts have been synthesized by the sol-gel method and have been characterized by a variety of physicochemical methods, including X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier-transform spectroscopy. The synthesized TiO2/CdS samples exhibit a high activity in the partial photocatalytic oxidation of ethanol to acetaldehyde under irradiation with visible light (λ > 420 nm) in a batch reactor. Their high activity can be due to heterojunctions occurring between cadmium sulfide and titanium dioxide nanoparticles and causing the separation of photogenerated charges.