In this study, bioactive glass powders were synthesized from four different types of oxides (SiO2, P2O5, CaO and MgO). These oxides were mixed, melted, milled and sieved to produce powders with two chemical compositions of the 31SiO2-11P2O5-(58-x)CaO-xMgO system. The powders were plasma sprayed onto AISI 316L stainless steel and Ti6Al4V titanium alloy substrates using a F4MB Sulzer Metco gun. The physical and mechanical properties of coatings, as well as their bioactivity were evaluated. The bioactivity tests were carried out exposing the surface of coatings to simulated body fluid (SBF) during 1, 9 and 15 days. The thickness and hardness of apatite layer produced on the surface of each coating during bioactivity tests were evaluated. The results indicate that the thickness of apatite layer formed during 15 days in SBF is between 31 and 51 µm and its hardness is between 1.5 and 1.9 GPa according to the chemical composition of feed stock powder used to manufacture the coatings. Additionally, the harness of bioglass coatings decreased around 26% after to expose them to SBF.