Phosphate-based glasses with different amounts of titanium dioxide (TiO2), having the following molar composition 50P2O5-30CaO-9Na2O-3SiO2-3MgO-(5-x)K2O-xTiO2, (where x = 0, 2.5, 5 mol %), were synthesised and characterized in terms of solubility (according to ISO 10993-14), and in vitro biocompatibility using human MG-63 osteoblast cells. Dissolution tests were carried out in Tris-HCl (pH 7.4) to simulate the physiological pH and in citric acid (pH 3.0) to simulate an acidic environment. The weight loss decreased with increasing TiO2 content, a process further enhanced in acidic medium. TiO2 reduced the pH changes usually caused by the dissolution products released. Cellular tests showed that all the glasses studied (0–5 mol % TiO2) and TiCl4, used to investigate the biocompatibility of titanium ions, did not produce cytotoxic effects on human MG-63 osteoblasts for up to 5 days in culture. On the basis of these results, we suggest that TiO2-containing phosphate glasses could be promising substrates for bone tissue engineering applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.