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Abstract Ordered carbon vacancies were detected in zirconium carbide (ZrC_x) powders that were synthesized by direct reaction. Zirconium hydride (ZrH₂) and carbon black were used as starting powders with the molar ratio of ZrH₂:C = 1:0.6. Powders were reacted at 1300°C or 2000°C. The major phase detected by x‐ray diffraction (XRD) was ZrC_x. No excess carbon was observed by transmission electron microscopy (TEM) in powders synthesized at either temperature. Ordering of the carbon vacancies was identified by neutron powder diffraction (NPD) and further supported by selected area electron diffraction (SAED). The vacancies in carbon‐deficient ZrC_xexhibited diamond cubic symmetry with a supercell that consisted of eight (2 × 2 × 2) ZrC_xunit cells with the rock‐salt structure. Rietveld refinement of the neutron diffraction patterns revealed that the synthesis temperature did not have a significant effect on the degree of vacancy ordering in ZrC_xpowders. Direct synthesis of ZrC_0.6resulted in the partial ordering of carbon vacancies without the need for extended isothermal annealing as reported in previous experimental studies.