Abstract: The effects of different environments and strain rates on the room temperature ductility of a TiAl based alloy with the composition Ti-46Al-2Cr-0.2Si-0.1Nd have been investigated in this paper. The results show that the TiAl based alloy is susceptible to environmental embrittlement at room temperature. The tensile ductility of the TiAl based alloy in difFerent test environments decreases in the sequence of oxygen> air>hydrogen>argon saturated with water vapor. The ductility is also sensitive to strain rate. It increases with increasing strain rate when tested in hydrogen gas. Both H2O and H2 cause environmental embrittlement, with the former being a more potent embrittler