Ultrafine TiC-15%Co powders were synthesized by a thermochemical process, including spray drying, calcination, and carbothermal reaction. Ti-Co oxide powders were prepared by spray drying of aqueous solution of titanium chloride and $Ti(OH)_2$ slurry, both containing cobalt nitrate, fellowed by calcination. The oxide powders were mixed with carbon powder to reduce and carburize at 1100~125$0^{circ}C$ under argon or hydrogen atmosphere. Ultrafine TiC particles were formed by carbothermal reaction at 1200~125$0^{circ}C$, which is significantly lower than the formation temperature (~1$700^{circ}C$) of TiC particles prepared by conventional method. The oxygen content of TiC-15%Co powder synthesized under hydrogen atmosphere was lower than that synthesized under argon, suggesting that hydrogen accelerates the reduction rate of Ti-Co oxides. The size of TiC-15%Co powder was evaluated by FE-SEM and TEM and Identified to be smaller than 300 nm.