WO₃ nanolamellae/reduced graphene oxide (RGO) nanocomposites have been synthesized by employing hydrothermal method where partial reduction in the graphene oxide and anchoring of nanolamellae on RGO sheets occur simultaneously. Nanocomposites with different amounts of RGO have been characterized by TEM, XRD, Raman spectroscopy, XPS, TGA-DTA, BET and PL spectroscopy. Chemiresistive sensors comprising of a thick layer of synthesized material have been fabricated on alumina substrates and investigated for acetone sensing. Sensing characteristics reveal that the sensor based on 2 wt% RGO nanocomposite not only exhibits high sensitivity, excellent selectivity and low optimum operating temperature but low detection limit (down to 1 ppm) as well. The mechanism for enhanced sensing performance of nanocomposite to acetone may be attributed to the presence of RGO sheets which facilitates large specific surface area for gas adsorption, superior conductivity, faster carrier transport and formation of heterojunctions at the interface between the RGO sheets and WO₃ nanolamellae.