Novel multi-walled carbon nanotubes (MWCNTs) grafted with poly(N-vinylcarbazole) electroconductive nanocomposites (PVK-g-MWCNTs) were prepared through nucleophilic reaction of PVK and MWCNTs in the presence of sodium hydride. The covalent interaction between PVK and MWCNTs and the dispersion properties of the prepared composites were characterized through Fourier transform infrared spectroscopy, thermal gravimetry, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses. Conducting nanocomposites were fabricated into thin films to detect their responses toward THF vapor. Experimental results indicated that the electroconductive nanocomposite film sensors exhibited good response and reproducibility toward THF vapor. Particularly, the chemically grafted PVK-g-MWCNTs sensor exhibited faster response and preferable recoverability compared with physically mixed sensor. Sensing properties were influenced by carboxyl content and solvent vapor concentration. The conductive nanocomposite sensors exhibited a satisfactory linear relationship between response and analyte concentration and a relatively low detection limit of up to 50 ppm. This study confirmed that covalently linked PVK-g-MWCNTs nanocomposites can be used to fabricate gas sensors for monitoring environmental gaseous pollutants. (C) 2016 Elsevier B.V. All rights reserved.