Gas sensors operating at room temperature have been fabricated from hybrid films of reduced graphene oxide (rGO) and iron doped (Fe-doped) WO3. Films with different rGO layer thicknesses (1-44 nm) obtained by vacuum filtration method were deposited on to a 250 nm thick sputtered Fe-doped WO3 film. Raman, XPS and SEM were used to investigate the morphology and composition of the films. The sensors were tested towards different concentrations of NO2 and relative humidity (RH%) at different temperatures ranging from 25 degrees C to 100 degrees C. The experimental results revealed that the highest response of the hybrid gas sensors towards these target gases is found to be for rGO layer thickness of 16 nm at room temperature. The sensing mechanisms of the hybrid films for different temperatures and rGO layer thickness were discussed based on the behaviour of the sensors towards the target gases. (C) 2017 Elsevier B.V. All rights reserved.