Indium-zinc oxide (IZO), with Zn/(Zn + In) = 0.33 - 0.78, films were deposited by the sol-gel method. Effects of Zn/(Zn + In) atomic ratio and annealing temperature on the structural, electrical and optical properties of IZO thin film were investigated. Films of Zn/(Zn + In) = 0.33 prepared at 600degreesC had the lowest resistivity value, 4.48 x 10(-2) Omega(.)cm (carrier concentration = 3.83 x 10(18) cm(-3) and mobility = 25.54 cm(2)/Vs), and the structure of these films matched that of Zn2In2O5 film. Average optical transmittances of all films were above 80% in the visible range. The highest average transmittance was observed at Zn/(Zn + In) = 0.5, with 86.8% in the visible range.