The optical properties and photovoltaic characterization of CdS quantum dots sensitized solar cells (QDSSCs) were studied. CdS QDs were prepared by the chemical solution deposition (CD) technique. Photoacoustic spectroscopy (PA) was employed to study the optical properties of the prepared samples. The sizes of the CdS QDs were estimated from transmission electron microscope (TEM) micrographs gives radii ranged from 1.57 to 1.92 nm. The current density‐voltage (J-V) characteristic curves of the assembled QDSSCs were measured. Fluorine doped Tin Oxide (FTO) substrates were coated with 20 nm‐diameter TiO2 nanoparticles (NPs). Presynthesized colloidal CdS quantum dots of different particles size were deposited on the TiO2‐coated substrates using direct adsorption (DA) method. The FTO counter electrodes were coated with platinum, while the electroelectrolyte containing redox species was sandwiched between the two electrodes. The short current density (Jsc) and efficiency (η) increases as the particle size increases. The values of Jsc increases linearly with increasing the intensities of the sun light which indicates the greater sensitivity of the assembled cells.