A detailed investigation of the structural and opto-electrical properties of tin-doped indium-zinc oxide thin film, prepared by pulsed laser deposition was carried out. The substitution of indium for tin in ZnkIn2Ok+3 compounds (k = 2, 3 and 5) (which structure is a mixture of homologous phases with different k, but mostly composed of the polytype ha in,, the target composition) led to a conductivity enhancement, caused by an increase in carrier concentration at low doping levels. whereas for higher doping levels a decrease in conductivity and carrier concentration together with an amorphisation of the film was noted. The best electrical properties (sigma=2500 S/cm) were obtained for the Zn2In1.9Sn0.1O5-delta doped films, having a layered ZnkIn2Ok+3-type structure with essentially k=2. Independently of the composition an 85-90% average transmittance in the visible region was obtained. In contrast the band gap of the Sn-doped film slightly increased with tin ratio. in agreement with the Burnstein-Moss theory.