The resistive response of atomic layer deposited thin epitaxial Î±-Cr2O3(0 0 1) films, to H2 and CO in air, was studied. The films were covered with Pt nanoislands formed by electron-beam evaporation of a sub-monolayer amount of the material. The gas measurements were performed at 250Â°C and 450Â°C. These temperatures led to different proportion of chemical states, Pt2+ and Pt4+, to which the Pt oxidized. The modification was ascertained by the X-ray photoelectron spectroscopy method. As a result of the modification, the response was fast at 250Â°C, but slowed at 450Â°C. A disadvantageous abundance of Pt4+ arising at 450Â°C in air could be diminished by high-vacuum annealing thus restoring the response properties of the system at 250Â°C.