In this work, we proposed a strategy to improve the damp-heat stability and weak-acid resistance of gallium doped zinc oxide (GZO) thin films by co-doping TiO2 into GZO targets. Results showed that GZO thin films with a 0.2 wt% TiO2 co-doping in the target (GTZO) exhibited a resistivity of 5.1 x 10(-4) Omega.cm and an average transmittance of 82.9%. The relative change in sheet resistance was as low as 5.1% after 24 h damp heat treatment in conditions of 97% relative humidity at 121 degrees C. A craterlike textured surface with a high haze value was not found in GTZO thin films after dipping in 1 vol% HCl solution for 10 min. These results showed that GTZO thin films have great potential for use as transparent electrode in extreme outdoor conditions. (C) 2017 Published by Elsevier B.V.