The dynamic tensile behavior of a newly developed Ti-6Al-2Sn-2Zr-3Mo-1Cr-2Nb-Si alloy (referred as TC21) over a wide range of strain rates from quasi-static to dynamic regimes (0.001-1250s-1) at different temperatures are experimentally investigated. A split Hopkinson tension bar apparatus and a static material testing system are utilized to obtain the stress-strain response under uniaxial tension loading condition. The experimental results indicate that the tensile behavior of TC21 titanium alloy is dependent on the strain rate and temperature. The initial yield stress increases with increasing strain rate. The effects of strain rate and temperature on the initial yield behavior are studied by introducing two rate sensitivity parameters. The phenomenologically based constitutive model (Johnson-Cook model) is suitably modified to describe the dynamic tensile behavior of TC21 titanium alloy. The predicted results of modified model are in good agreement with the experimental data subjected to the investigated range of strain rates and temperatures.