Synthesis of titanium diboride has been carried out using thermal plasma processing technique. Thermody- namic simulations have been carried out to determine the molar ratio of the reducing gas to be used in TiO2-B2O3- CH4 system. The reducing gas used was methane and the molar ratio of reducing gas to that of the solid feed was varied between 4 and 7. The maximum yield of TiB2 of about 40 mol% was obtained with a feed molar ratio of TiO2 W B2O3 W CH4 D 1 W 1 W 5 and a power of 23.4 kW. Relatively higher solid feed rates (5:367 � 10 � 5 kg= si n- stead of 3:583 � 10 � 5 kg=s) increased the yield of TiB2. The TiB2 spherical particles formed are in the range of 20- 100 � 10 � 9 m. A change in crystal structure was observed in TiO2 from anatase to rutile. The formation and amounts of product powders are discussed and compared with theo- retical calculations.