This research is intended to study the photo-electric and thermal characteristics of CdS thin films. These films were fabricated using vacuum thermal evaporation techniques. The prepared samples were found to have a good light response. It is observed that the photocurrent is linearly proportional to the film thickness, substrate temperature and annealing temperature up to 250 degrees C where at this temperature maximum photocurrent (40 mu A) was obtained. Also, the photocurrent is inversely proportional to the deposition rate. 12000 Angstrom film thickness has been choosen because it has the minimum resistivity which gives the best photo-electric and thermal response. Two values of activation energy, lying between (0.064-0.28)eV for temperature range (293-473)K for different deposition parameters were obtained. Also, it was found that this energy decreased as annealing temperature increased up to 250 degrees C indicating that the carrier concentration increases with annealing temperature.