Highly sensitive, Si-integrated gas sensors based on undoped, In- and Sb-doped nanocrystalline SnO 2-films, have been fabricated by spray pyrolysis. We have found that the In-doped gas sensors show significantly improved sensitivity for CH 4 detection and low sensitivity for H 2 detection, while Sb-doped sensors exhibit high sensitivity towards H 2 and comparatively low sensitivity for CH 4 detection. The results demonstrate that a device implementing both a In-doped SnO 2 sensor as well as a Sb-doped sensor should be capable for well defined discrimination of CH 4 and H 2-gases when mixed to synthetic air as background gas. This indicates that proper doping of SnO 2-films is a powerful strategy for the future realization of Si-integrated multi-gas sensor systems.