In order to clarify the effect of nonstoichiometry on the high-temperature deformation behavior of titanium carbide, single crystals having a wide range of C/Ti atom ratios, x, 0.59 to 0.95, were deformed by compression in a temperature range of 1180∼2270 K and in a strain rate range of 2×10⁻⁴∼6×10⁻³ s⁻¹. It is found that the high-temperature deformation behavior observed is divided into two groups: One is the x-independent or less-dependent type, including the existence of two temperature regions with different deformation mechanisms, the form of mechanical equation at yielding and the work hardening behavior. The other is the x-dependent type, including the yielding behavior, the critical resolved shear stress, τ_c, the activation energy for deformation and the stress exponent of strain rate, m. In particular at lower C/Ti ratios, most of the behavior in the latter group exhibits a remarkable x-dependence; e.g., around TiC_0.75 τ_c shows a peak and a very marked work softening occurs, whereas at TiC_0.59 τ_c is the lowest and work softening is less clear.