Thin films of ZnO were electrodeposited on flexible stainless steel (SS) substrate from a Ga-containing ZnCl2 solution. The films morphology, structure, and photoluminescence properties are briefly discussed. For the electrical characterization of the films, metal-semiconductor (MS), and metal-insulator-semiconductor (MIS) devices of type Ag/ZnO/SS and Ag/SiOx/ZnO/SS were fabricated and their parameters were determined by the means of current-voltage and capacitance-voltage measurements. Devices with a reasonably good built-in potential, barrier height, and rectification factor were achieved, and the concentration of donors, N-d, in the films was evaluated. Results revealed that N-d increases from similar to 10(15) to similar to 10(18) cm(-3) by annealing the films in oxygen at 400 degrees C. Furthermore, it was observed that the hydrogen peroxide treatment of the films lowers the N-d value by a factor of 10-100 and yields a large electron mobility. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3521311] All rights reserved.