An explorative study was performed on sputter-deposited thermochromic (TC) VO2 films exposed to heat treatment under dry and humid conditions. The ambient conditions were harsh and 80-nm-thick VO2 films were rapidly converted to non-TC V2O5. It was found that a 30-nm-thick sputter-deposited Al oxide top coating provided good protection and delayed the oxidation for more than one day upon heating in dry air at 300 degrees C and that protection occurred for several days at 95% relative humidity and 60 degrees C. The thickness of the Al oxide was important and, expectedly, increased thickness yielded enhanced protection. Our results are important for TC fenestration as well as for other technical applications. (C) 2014 Elsevier B. V. All rights reserved.