Thin films of indium tin oxide doped with ZnO thin films have been prepared by the electron-beam evaporation technique. The effects of heat treatment and ZnO content on the structural, optical and electrical properties of these films have been investigated. The optical transmission was found to improve with increasing ZnO ratio and annealing temperature. Enhancement of the film crystallinity or the grain size growth seemed to be associated with an improvement of the mobility carriers and hence the film conductivity. Transmittance values of 84–90% in the visible region and low electrical resistivity of 1.2 × 10−4–1.3 × 10−4 cm have been achieved for (ITO)1−x(ZnO)x film with x = 0.2 annealed at temperature of 325 ◦C for 90 min and 120 min, respectively. Other optical parameters, namely optical energy gap, free carrier concentration, refractive index and extinction coefficient were studied.