Photoelectrical properties of heterojunctions based on transparent oxide semiconductor (TOS) thin films-semiconductor (S) are outlined. The structures consisted of transparent thin films of TiO2 doped with V and Pd (n-type semiconductor) and TiO2 with Co and Pd (p-type semiconductor) deposited by magnetron sputtering on standard silicon wafers (p-type and n-type respectively). The structures were examined by means of cuffent-voltage (I-V) measurements and the Optical Beam Induced Current (OBIC) method. Temperature dependent I-V characteristics displayed a strong non-linear behaviour of prepared TOS-S heterojunctions. (C) 2007 Published by Elsevier B.V.