Quantum dots are very tiny semiconductor particles used in solar cells; their optical and electronic properties differ from those of macro particles. They could improve the performance of solar cells if they are prepared in the suitable size. In this work, cadmium sulfide (CdS) quantum dot (QD) thin films were prepared on transparent conductive fluorine-doped tin oxide substrates. The formation and deposition of CdS QDs were optimized using the chemical bath deposition method under varied operating conditions (precursor concentration, and temperature). Chemical bath deposition is an effective method for the deposition of CdS on porous TiO2 films as QDs. The structural, morphological, and optical properties of the prepared CdS thin films were studied using X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy and UV-Vis-near infrared spectroscopy. The particle size of the CdS QDs was calculated to be 3–7 nm from the observed X-ray diffraction pattern. The band gap was blue shifted in the UV-Vis absorption spectrum compared with that of bulk CdS, confirming the formation of CdS QDs.