In our present study, Ce doped CdS nanoparticles were synthesized in room temperature environment by using chemical co-precipitation technique which is cheap in cost. Ce doped CdS nanoparticles (average particle size: 3.7 nm) were found to have cubic structure as a result of XRD measurements. It has also been clearly observed that Ce dopant ions do not alter the structure of the host semiconductor CdS. Using the spectrum obtained as a result of UV-Vis measurement, the energy band gap of Ce doped CdS nanoparticles was determined as 2.73 eV. This value was observed to be higher than the energy band gap of bulk CdS (2.42 eV). Thus, it can be said that this change in the energy band gap is due to the quantum confinement effect. The maximum IPCE value was 27% for Ce doped CdS nanoparticles while the IPCE values was 4% for pure CdS nanoparticles, respectively. The IPCE of the solar cells improves with the Ce dopant ion. Moreover, the spectral response range of Ce doped CdS nanoparticles widens with the Ce dopant ion. This is attributed to the long lifetimes of the Ce3+ excited states that facilities the transfer of the charge carries to the photoelectrode.