Temperature has strong effects on the leaching behavior of the 90-19/U simulated high-level waste glass form. The Arrhenius equation is used to determine the change in the glass corrosion mechanism throughout the different temperature ranges. The apparent activation energies have been obtained for different leaching conditions. In deionized water, the glass corrosion mechanism is similar whether the leaching condition is static or dynamic. The glass corrosion process is dominated by the ion exchange reactions at lower temperatures (60 to ~70°C); however, the glass corrosion process is dominated by the network hydrolysis reactions at higher temperatures (>70°C). The apparent activation energy in the lower temperature range is larger than that of the higher temperature range. In simulated underground water, the ion exchange reactions dominated the glass corrosion mechanism at temperatures from 50 to 150°C, and the large amount of ions in simulated underground water would participate in the ion exchange reactions with the glass.