Abstract <p>The conditions of formation of MoO₂/C composites synthesized by microwave-assisted hydrothermal treatment of a mixture of peroxomolybdic and tartaric acids with subsequent annealing of precursors in an inert atmosphere have been studied. The use of tartaric acid as a source of the carbon component of the composite enables the synthesis of MoO₂/C with a carbon content of up to 15.1 wt %. Key physicochemical characteristics of MoO₂/C composites have been determined by X-ray powder diffraction analysis, vibrational and X-ray photoelectron spectroscopy, electron paramagnetic resonance, thermogravimetric and chemical analysis, scanning electron microscopy, low-temperature nitrogen adsorption, and the pycnometer method. It has been found that the composition and textural and thermal properties of the composites are determined by the content of tartaric acid in the reaction mass; varying the tartaric acid content makes it possible to obtain MoO₂/C with various degrees of defectiveness and graphitization of the carbon component of the composites. A possible mechanism for the formation of MoO₂/C composites is proposed.</p>