The objective of this study is to evaluate the high temperature behavior of γ TiAl-based alloy sheets containing AI2O3 particles, produced by a combination of vacuum induction melting, use of a CaO crucible, and direct sheet casting, over a wide temperature range. Alumina particles, having a tendency to coagulate during solidification of a TiAl ingot, are finely dispersed due to the disturbance of high frequency induction, and frozen without having enough time to grow in size by direct sheet casting. The TiAl sheet thus produced shows remarkable high temperature tensile strength which exceeds that of conventional ingots having the same composition and various different structures. This is determined to be attributable to the dispersion strengthening of finely dispersed AI2O3 particles whose diameter is from 100 to 500nm. Moreover, because of the small size of these alumina particles, the TiAl sheet does not show any significant retardation in high temperature ductility, which is often the case in conventional ceramic-reinforced intermetallic compound composites.