Abstract: A glass composition for use in pH-responsive glass electrodes, and a glass electrode having a pH-responsive membrane of such glass, which composition consists essentially of (in mole percent on the oxide basis):a. from about 30 to about 37 mole percent Li.sub.2 O;b. from 0 to about 4 mole percent of at least one oxide selected from the group consisting of Cs.sub.2 O and Rb.sub.2 O;c. from about 2 to about 12 mole percent of at least one oxide selected from the group consisting of La.sub.2 O.sub.3 and Pr.sub.2 O.sub.3 ;d. from about 2 to about 10 mole percent of at least one oxide selected from the group consisting of Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 ;e. from 0 to about 4 mole percent UO.sub.2 ; andf. the balance SiO.sub.2 ;with the proviso that there is present in the composition at least about 2 mole percent of at least one oxide selected from the group consisting of Pr.sub.2 O.sub.3 and Nb.sub.2 O.sub.5.