The 1100 degrees C isothermal section and the isopleths at 5, 10, and 15 at.% C in the Ti-Si-C system were determined by DTA and XRD methods. Five invariant reactions (L (liquid) = Si + SiC + TiSi2 at 1330 degrees C, L = TiSi + TiSi2 + Ti5Si3Cx at 1485 degrees C, L + Ti5Si3Cx = Ti3SiC2 + TiSi2 at 1485 degrees C, L + Ti3SiC2 = TiSi2 + SiC at 1473 degrees C, and L + TiC = bcc-(Ti) + Ti5Si3Cx at 1341 degrees C) were observed. The transition temperature for L + TiC = Ti3SiC2 + SiC was measured by the Pirani technique. Optimized thermodynamic parameters for the Ti-Si-C system were then obtained by means of the CALPHAD (calculation of phase diagrams) method applied to the present experimental results and reliable literature data. The calculations satisfactorily account for most of the experimental data.