The carbon vacancy mobility has been calculated from the high temperature (1700 K-3000 K) carbon tracer diffusion data obtained for monocrystals of TiC1-x with different carbon vacancy concentrations and compared with values calculated from chemical diffusion coefficients determined also on monocrystals of TiC1-x in the same temperature range. The mobility of carbon vacancies in TiC1-x and its activation energy are very characteristic functions of the carbon vacancy concentration, indicating the existence of strong repulsive interactions between carbon vacancies and even stronger attractive interactions between titanium ions having the opposite influence on the structure sensitive properties of TiC1-x.