The hot deformation behavior of Ti-15-3 titanium alloy was investigated by hot compression tests conducted in the temperature range 850-1150 degrees C and strain rate range 0.001-10 s(-1). Using the flow stress data corrected for deformation heating, the activation energy map, processing maps and Zener-Hollomon parameter map were developed to determine the optimum hot-working parameters and to investigate the effects of strain rate and temperature on microstructural evolution of this material. The results show that the safe region for hot deformation occurs in the strain rate range 0.001-0.1 s(-1) over the entire temperature range investigated. In this region, the activation energy is similar to 240 +/- 5 kJ/mol and the ln Z values vary in range of 13.9-21 s(-1). Stable flow is associated with dynamic recovery and dynamic recrystallization. Also, flow instabilities are observed in the form of localized slip bands and flow localization at strain rates higher than 0.1 s(-1) over a wide temperature range. The corresponding ln Z values are larger than 21 s(-1). The hot deformation characteristic of Ti-15-3 alloy predicted from the processing maps, activation energy map, and Zener-Hollomon parameter map agrees well with the results of microstructural observations.