Differential thermal analysis (DTA) under nonisothermal conditions was carried out on glasses of xFe 2 O 3 (80−x)Bi 2 O 3 ·20Ga 2 O 3 system (x=0, 5, 10, 20 mol%). The crystallization has been studied by using DTA. From the dependence of the glass transition temperature (T g ) on the heating rate (a), the glass transition activation energy (E a ) was derived. Iron oxide addition to gallium-bismuthate glass matrix induces minor changes in glass thermal stability but causes continuous decrease of melting temperature.