Different kinds of bioactive materials are used as bone substitutes. In particular, bioglasses containing Si, Ca, Na and P, bind to host tissues with a stable chemical bond. The phenomenon of bioactivity is associated with the formation of a crystallized hydroxycarbonated apatite (HCA) layer on the bioglass surface, when soaked in a simulated physiological fluid. This layer is similar to the mineral phase of bone. Synthesized bioglasses have been obtained using organic modifiers instead of mineral modifiers, which are the usual precursors for sol-gel synthesis. First, a slightly soluble ternary glass, containing 48% CaO, 5% P2O5 and 47% SiO2, referred to as Si47P5T, was prepared. Then, some sodium oxide has been added to obtain a more bioactive quaternary bioglass, containing 21.5%Na2O, 26.5% CaO, 5% P2O5 and 47% SiO2 which is referred to as Si47P5Q. Physicochemical properties of both bioglasses have been studied. Bioactivity in a simulated body fluid (SBF) and cytotoxicity tests have complemented the study. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.