Understanding the physics of chip formation in machining operations is often difficult due to the complexity of the phenomena involved, such as the extreme and complex loading conditions that occur in the cutting zone. In order to model the machining process, it is necessary to use a constitutive behavior law that is capable of reproducing as accurately as possible the behavior of the material under these extreme conditions. In this context, this paper presents a study of the mechanical behavior of the Ti17 titanium alloy at high strain rates and high temperatures. This has been achieved by undertaking compression and shear tests over a wide range of strain rates (from 10−1 s−1 to 100 s−1) and temperatures (from 25 to 800 ◦C). The results show that the Ti17 alloy is sensitive to strain rate, especially for strain rates greater than 1 s−1. In addition, the alloy retains good mechanical properties at high temperature (up to 500 ◦C). Based on the experimental results, the parameter of the Johnson-Cook constitutive equation have been identified using the inverse method. Some weaknesses in the model have been highlighted after the identification phase, especially in terms of the m and C parameters. A modification of the model has been proposed.