Highly transparent and conductive Zn2In2O5 films have been prepared by d.c. magnetron sputtering using targets composed of ZnO and In2O3. The films deposited on substrates at a temperature of 350 degrees C using targets with a composition (Zn:(In + Zn) atomic ratio) of approximately 20 to 60 at.% were identified as Zn2In2O5. The etching rate of the films in a HCl solution was strongly dependent on the Zn:(In + Zn) atomic ratio and the substrate temperature. Zn2In2O5 films deposited on substrates at a temperature of room temperature to 350 degrees C exhibited a resistivity of 2-4 x 10(-4) Omega cm. An average transmittance of above 85% in the visible range was obtained in the films.