Undoped and silver, lithium and cobalt-doped ZnO thin films have been successfully deposited on glass by chemical bath deposition (CBD). The reaction temperature was 50 degrees C and the films were annealed at 400 degrees C for 4h in a high temperature furnace. UV/VIS spectrum was used to determine optical transmittance, optical band gap (E-g) and absorbance values of Ag:ZnO, Co:ZnO, Li:ZnO and undoped ZnO thin films. Optical band gap (E-g) and absorbance values of undoped ZnO, Ag: ZnO, Co:ZnO and Li:ZnO thin films were found as 0.0158, 0.0064, 0.2638, 0.0956 and 3.24, 3.13, 3.27, 2.96 eV, respectively. Extinction coefficients and refraction indexes of the films were found to be 0.0096, 0.0038, 0.0068, 0.019 (extinction coefficient) and 1.26, 1.14, 1.66, 2.33 (refraction index), respectively. X-ray patterns of undoped ZnO, Ag:ZnO, Co:ZnO and Li:ZnO thin films were confirmed as amorphous.