We have investing the effect of annealing treatment of CdO films, deposited by chemical deposition using successive ionic layer adsorption and reaction (SILAR) technique , on the film properties . The CdO thin film were Prepared by using cadmium acetate at concentration (0.03M) and base solution from ammonium hydroxide solution on glass substrate. .It's found that the optical, electrical and gas sensing (H2, CO) properties of the films are effected by the annealing temperature.