Cadmium Selenide (CdSe) thin films of different thickness were deposited on ITO (Indium-Tin Oxide) and glass substrates using the Chemical Bath Deposition (CBD) method at 50 o C and 3h time, which employs a bath containing Cadmium acetate ((CH 3 COO) 2 Cd. 2H 2 O) and Sodium Selenosulfate (Na 2 SeSO 3 ) solution as a source of Cd +2 ions and Se -2 ions respectively. The cleaned substrates were immersed at an oblique angle~(15 o -20 o ) in the final solution. The optical and electrical characteristics of these thin films were investigated using a UV-Vis spectrophotometer and a silver probe setup with a current-voltage (I-V) source meter. Optical studies revealed that the CdSe thin films had a straight band gap that decreases with thickness from 2.14 to 1.9 eV.The electrical study (I-V characteristics) revealed a linear relationship between voltage and current, indicating the formation of ohmic contact between the conduction electrodes (Ag and ITO) and the semiconducting CdSe layer. Furthermore, increasing the illumination intensity from (30-60 watts) increases the sensitivity of the film to light, resulting in the formation of electron-hole pairs that contribute to conduction. Furthermore, when the thickness of the CdSe film increases, the photosensitivity increases from (0.21-0.27) and (0.24-0.28) for 423nm and 631nm CdSe thin film thickness, respectively.