A thermal plasma jet has been used for the synthesis of ultrafine TiO2. As source material, TiCl4 was injected with vapor phase by Ar-carrier gas and with liquid drop by micro pump. Particle compositions were observed for reactor configuration, collecting position, plasma power, and various flow rates of raw material, respectively. The characteristics of the powder such as particle size, size distribution, and phase composition were analyzed with XRD, SEM, TEM, EDS, DTA and particle size analyzer. When TiCl4 was injected with the vapor phase, the rutile content of the powder increased with the how rate of Ar-carrier gas and input power. In the case of injecting liquid phase TiCl4, particle compositions were not affected by the flow rate of TiCl4. Most of the powder was mainly composed of anatase. However, the powder obtained on the A-type reactor wall was observed with 95% rutile. Also, we have investigated the phase transformation phenomena of anatase-to-rutile. After heat treatment, the anatase-to-rutile transformation started at approximately 600 degreesC and completed at 1000 degreesC. The size of the powder and particle agglomeration depended on the flow rate of TICl4 and quenching gas. Most of the powders were white-colored and their average diameter increased from 20 to 300 nm according to the flow rate of TiCl4.