Investigations are made on the effects of strain rates on the tensile behavior and deformation modes of Duplex Ti-46.5Al-2Nb-2Cr (DP TiAl) at temperatures ranging from room temperature to 840 A degrees C and under strain rates of 0.001, 320, 800, and 1350 s(-1). The dynamic strength is higher than quasi-static strength but does not change much over the high strain rate range. Yield stress anomaly is not found. Brittle-to-ductile transition temperature (BDTT) increases with the increased strain rates. A Zerilli-Armstrong constitutive model with appropriate coefficients is chosen to describe the high strain rate flowing behavior. TEM analysis indicates that both ordinary dislocations and superdislocations are found and dislocation pile-up only appears in samples deformed under quasi-static loadings at elevated temperatures. The deformation twins are common in equiaxed grains and the proportion of twinned grains increases with the increased strain rate from 46-72% under quasi-static loadings to 69-95% under high strain rate loadings. No deformation twins are found in lamellar colonies.