Tungsten carbide nanoparticles (NPs) were synthesized by wire explosion process (WEP) in gas ambient as carbon source. Formation of tungsten carbide (WC1− X) in a single step by WEP using methane and argon-acetylene mixture as carburizing medium, is detailed. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to observe the phase and morphology of the produced NPs. In WEP, morphology and phase of NPs are controlled using different levels of energy ratio, K (ratio of energy supplied to wire and sublimation energy of wire), type and pressure, P of ambience. High purity WC1− X NPs was synthesized in methane ambience with a high K (=19) and a high P (270 kPa). A thorough study has been made to understand the impact of type of carburizing medium. Methane-acetylene mixture gave two phases of carbides. Argon-acetylene ambience provided complete carburization in specific cases. In general, the formed NPs are spherical in shape. Formation mechanism of tungsten carbide NPs is detailed in the work. © 2019 The American Ceramic Society