Hexane-insoluble coal tar pitch was converted into mesophase pitch by heat treatment in the range of 410-450℃, and its optical anisotropy and solubility were investigated to see the formation of mesophase. The C/H ratio was about 2.33 and the optical texture was classified as a mixture of small domain(SD) and flow(F) when the pitch was heat treated at 450℃, 7hrs. Quinoline insolubles of mesophase pitch was mainly from benzene solubles, and the sum of benzene insolu-bles/pyridine solubles and pyridine insolubles/quinoline solubles was maintained almost constant during the heat treatment of the pitch.