Chromium selenide (CrSe) crystalline thin film produced with chemical bath deposition on substrates (commercial glass). Transmittance, absorption, optical band gap and refractive index investigated UV/VIS. Spectrum. The hexagonal form observed of structural properties in XRD. The structural and optical of CrSe thin films were analyzed at different pH. SEM and EDX analysis studied for surface analysis and elemental ratio in films. Some properties of films changed with pH and these properties investigated change of pH. The pH values were scanned at 4-9. The optical band gap changed with pH between 3.70 to 3.86 eV. Also, the film thickness changed with pH at 761 nm to 889 nm. The transmission was coherent with the film thickness 82.41, 88.30, 92.47 and 79.06 % (550 nm wavelength) which were at 865, 761, 785 and 889 nm, respectively. Refractive index changed with the film thicknesses at 1.59, 1.45, 1.34 and 1.67 (550 nm wavelength) which were at 865, 761, 785 and 889 nm, respectively.