The effect of processing parameters on the flow response and microstructural evolution of the a+b titanium alloy Ti-6.5Al-3.5Mo-1.5Zr-0.3Si has been studied by conducting isothermal hot compressive tests at a strain rate of 0.01-10 s-1 at 860-1100°C. The true stress-true strain curves of the sample hot-compressed in the a+b phase region exhibit a peak stress followed by continuous flow softening, whereas in the b region, the flow stress attains a steady-state regime. At a strain rate of 10 s-1, the alloy exhibits plastic flow insta-bilities. According to the kinetic rate equation, the apparent activation energies are estimated to be about 674-705 kJ/mol in the a+b region and 308-335 kJ/mol in the b region, respectively. When deformed in the a+b region, the globularization process of the a colony structure occurs, and a dynamic recrystallized microstructures are observed to show bimodal. Dynamic recrystallization can take place in the b region irrespective of starting deformed structures. The effect of processing parameters on the flow response and microstructural evolution of the a + b titanium alloy Ti-6.5Al-3.5Mo-1.5Zr-0.3Si has been studied by conducting isothermal hot compressive tests at a strain rate of 0.01-10 s -1 at 860-1100 ° C. The true stress-true strain curves of the sample hot-compressed in the a + b phase region exhibit a peak stress followed by continuous flow softening, but in the b region, the flow stress attains a steady to state regime. At a strain rate of 10 s-1, the alloy exhibits plastic flow insta-bilities. According to the kinetic rate equation, the apparent activation energies are estimated to be about 674-705 kJ / mol in the a + b region and 308-335 kJ / mol in the b region, respectively. When deformed in the a + b region, the globularization process of the a colony structure occurs, and a dynamic recrystallization microstructures are observed to show bimodal. place in the b region irrespective of starting deformed structur es.