The glass forming region of TiO 2 ZnOP 2 O 5 glasses was investigated at 1400°C, which is lower than the melting temperature of general titanophosphete glasses. TiO 2 could be added up to 15 mol% in the TiO 2 ZnOP 2 O 5 glasses. The glass forming region of 15TiO 2 ZnOP 2 O 5 was quite smaller than that of ZnOP 2 O 5 , and the glasses with TiO 2 were colorized by the formation of Ti 3+ . The refractive index of the glasses increased with increases in the TiO 2 concentrations, and the maximum was 1.656. The glass transition temperature, T g , of the glasses increased with increased TiO 2 concentrations, although T g decreased with increases in the ratio of ZnO to P 2 O 5 . Raman spectra of the glasses suggested that POTi bonds were formed by the addition of TiO 2 . The increase in T g and the narrow glass forming region were caused by the formation of strong chemical bonds, POTi.