Glasses corresponding to mole formulas R2TiO3 and R2Ti2O5 were prepared in 1- to 5-g quantities by quenching in a platinum crucible. K2O, Rb2O, and Cs2O formed fairly stable glasses with TiO2. On heat treatment, these glasses nucleated readily and formed opal-like glasses. Li2O and Na2O, however, did not form glasses with TiO2 in 1-g quantities. Hygroscopicity increased with the alkali content and decreased with the increase in TiO2 concentration. The refractive indices of the glasses ranged from 1.66 to 1.90. These facts indicate that TiO2 is a glass former in its own right and that Ti4+ exists in sixfold coordination in these glasses.