Vapor phase hydration studies of the inactive simulated French nuclear waste glass SON68 were conducted at temperatures ranging from 35 to 125°C and various relative humidities (RH). The purpose of this work was to understand the behaviour and to determine the alteration kinetics of SON68 glass under a non-saturated environment. Fourier Transform Infra-Red spectroscopy (FTIR) technique was used to follow the glass hydration kinetics. The glass hydration increased with increasing temperature and relative humidity. In addition to a hydrated glass layer calcite, powellite and apatite were identified.