This research is based on the study of thermal behaviour of bioactive glass in the quaternary system SiO2-CaO-Na2O-P2O5 doped with metallic elements such as Zn and Sr destined for use as bone biomaterial. It encompasses glass transition temperature, crystallization temperature and melting temperature. This work is based on both determination and comparison of the effects of Zn and Sr on thermal characteristics after their introduction in the glass matrix. Thermal stability and excess entropy of all studied glasses have been calculated. Obtained results highlight the different effects of doping on the glasses thermal behaviour. Most notable effects are the sharp decrease of melting temperature of 10 wt% Zn-doped glass and the increase of crystallization temperature of 10 wt% Sr-doped glass. Furthermore, excess entropy of pure glass increases with addition of Sr and decreases with addition of Zn.