Cu-ZSM-5 type molecular sieves were synthesized hydrothermally in weak acid medium in the presence of F- ions. The structures of these samples were investigated.Increasing the amount of copper in synthesized samples the unit cell volumes of Cu-ZSM-5 zeolites increase, while the adsorption peaks of Cu-ZSM-5 shift to lower wavenumbers.These facts and the results of the electron probe micrograph and XPS analyese indicate that copper was introduced into the framework of molecular sieve.