The paper dwells on the research conducted into high-rate consolidation of pure tungsten carbide (WC) nanopowders using the Spark Plasma Sintering technology. Studies included the effect that the original size of WC nanoparticles and their preparation modes have on density, structure parameters, and mechanical properties of tungsten carbide. Samples of high-density nanostructured tungsten carbide characterized by high hardness (up to 31–34 GPa) and improved fracture toughness (4.3–5.2 MPa m1/2) were obtained. It has been found that materials that show abnormal grain growth during sintering have lower values of sintering activation energy as compared to materials the structure of which is more stable during high-rate heating. A qualitative model is proposed that explains this effect through the dependence of the grain boundary diffusion coefficient on the grain boundary migration rate. •Samples of nanopowders tungsten carbide were made using DC arc plasma synthesis.•Samples of ceramic WC with high mechanical properties were made using the SPS.•Abnormal grain growth while SPS tungsten carbide stems from α-W and W2C particles.•Under abnormal grain growth, the values of the SPS activation energy are low.