Graphene/SnO2 and multi-walled carbon nanotubes (MWCNT)/SnO2 composites are synthesized by sol–gel process on adding 0.2 weight% of graphene and MWCNT into the precursor sol. The gas response of these composite was measured at room temperature. The resistance of these composite increases in presence of NO2 suggests their behavior as n-type semiconductor. The graphene/SnO2 sensor showed higher response and rapid response to NO2 in comparison to MWCNT/SnO2 or SnO2 at room temperature.