Titanium alloys absorb large amounts of hydrogen atoms (protium) which are desorbed in vacuum at elevated temperatures. The treatment utilizing this phenomenon is called protium. treatment. Our studies of this treatment are reviewed and recent experimental results are introduced. Protium treatment consists of the following three processes. for alpha+beta type titanium alloys: (1) protium absorption, (2) martensitic transformation and hot working, and (3) final treatment for protium desorption and recrystallization. A combination of these processes results in the ultra-fine grains of 0.3 to 0.5mum in diameter with high angle boundaries. The ultra-fine grained material shows improved 0.2% proof stress at room temperature and exhibits a superplastic elongation of over 9000%. Superplastic forming was successfully used to fabricate a denture base without cracks on the surface. These materials may be applicable as biomaterials in medical industries.