Abstract: A Ti-12Co-5A1 alloy sheet with an ultra fine α-Ti+Ti₂Co microstructu was obtained after a proper melting process and thermomechanical treatment. The all under this state exhibits very large superplastic elongation at relatively low temperature ar high strain rates. The elongation more than 1 500% was obtained at a strain rate of 3×10^-2s^-1 and 700℃. The superplastic deformation induced the size increase and shape chan of Ti₂Co intermetallic particles. No cavity was found in the specimen after superplast deformation to 500%.