In this study, ZnO nanopowders and ZnO doped with metals (Cu , Ag- doped ZnO) and (Cd, Ag- doped ZnO) were synthesized by the sol-gel method in order to investigation on the codoping effect on the band gap and photocatalytic activity of ZnO. The synthesized samples are characterized by IR spectroscopy technique. Moreover, the absorption coefficients of the ZnO, Ag-Cd-ZnO and Ag-Cu-ZnO were anal...