2 at.% Ga-doped MgxZn(1-x)O (x = 0-8%) films have been prepared by sol-gel dip-coating method, and the effects of three different post annealing ambient: (a) vacuum annealing under air pressure of similar to 10(-2) Pa; (b) annealing in nitrogen atmosphere, and (c) annealing in argon-hydrogen (96% argon + 4% hydrogen) atmosphere on the electrical and optical properties of the films are investigated. When treated by these three different post-annealing ambient, both the resisitivity and band gap of the films increase with Mg doping contents increasing from 0 to 8 at.%. The vacuum annealed films show much lower resistivity than those treated in nitrogen or argon-hydrogen atmosphere, and the transmittance of the vacuum annealed films (similar to 70%) is also lower than those annealed by the other two methods (similar to 90%) in visible region. It shows that different post annealing ambient and ion doping could modify the optoelectronic properties of ZnO films. (C) 2012 Elsevier B.V. All rights reserved.