In this US Bureau of Mines study, a variety of TiAl based composites were produced in situ by reaction synthesis. Mixtures of elemental Ti, Al and B and Ti, Al, and Si powders were reactive hot-pressed to form TiAl reinforced with 10, 20, 25 or 60 vol. pct. TiB2 or Ti5Si3. Microstructural evaluation of the resultant composites confirmed that the reaction products were primarily TiAl and TiB2 or Ti5S3, with a small amount of Ti3Al. The hot-press temperature and pressure had a significant effect on the density of the composites. In general, higher temperatures and initiating the reaction under pressure promoted dense composites. Room temperature biaxial flexure strength tests indicated that the addition of the reinforcing phases can improve the strength of TiAl. Potentiodynamic experiments revealed that TiAl, TiAl+TiB2 and TiAl+Ti5Si3 composites display active-passive corrosion behavior in both acidic and alkaline solutions.