Effect of hydrogen introduction into some metal oxide and nitride thin films was examined. Modification of electrical and optical properties by hydrogen introduction was examined on SnO2, Sn-GeO2, Ge-CdO2, ZnO. Electrical resistance could be reduced in some films without loosing their transparence to the visible light. Hydrogen introduction to Cu3N changed the film an electrical conductor. Films of AIN and TiN were rather insensitive to the hydrogen introduction; the hydrogen effect was only observed when the nitrides contain some imperfection in the compounds. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.