Ti3SiC2 has been known as a remarkable material for a myriad of applications because it displays both metallic and ceramic properties. Like metals, it has excellent electrical and thermal conductivities, high toughness, high fatigue-crack growth threshold, low hardness, machinability, and high-thermal shock resistance. Like ceramics, it displays excellent chemical resistance, high Young's modulus, high temperature strength and high melting point. Ti3SiC2 has been synthesized by hot pressing or hipping process using various starting material systems such as Ti/SiC/graphite [1], Ti/Si/C [2-4] and TiC/Si/Ti [5] powders. However, the synthesis of high purity Ti3SiC2 is not easy since a relatively long reaction time at high temperature is required to synthesize thermodynamically stable Ti3SiC2 through the formation of intermediate phases. Many works were recently conducted on the oxidation of Ti3SiC2-base materials for utilizing them as high temperature components such as an inter-connecter material for solid oxide fuel cell, since Ti3SiC2 has excellent electrical conductivity as well as relatively good oxidation resistance at the intermediate temperature. However, the oxidation behavior of Ti3SiC2 has not been fally understood yet [1-7]. The aim of this study is to characterize the high temperature oxidation of fine- and coarse-grained Ti3SiC2 materials, which were prepared by hot pressing using the newly developed TiC0.67 and Si powder mixture starting material system.