Mechanical behavior and microstructure evolution of Ti and Ti-64 titanium alloy during warm “abc” deformation has been studied. The “abc” deformation was consisted of successive compression of a sample along three orthogonal directions. Mechanical behavior of each material was described by set of successive σ-ε curves combined into cumulative σ-Σε curve. Microstructure of Ti was found to be refined to a grain size of about 0.4 μm due to formation of deformation-induced boundaries within initial grains. Although a stage like steady state flow was observed at the cumulative σ-Σε curve such mechanical behavior was hardly associated with superplastic flow. In two-phase Ti-64 alloy the structure was found to be refined to a grain size of about 0.4 μm after warm “abc” deformation due to globularization α- and β-particles following breaking down of α-lamellar and β- layers. Microstructure refinement of the alloy was associated with softening and superplastic flow.