Calcium silicate (CaSiO3) is regarded as a potential bioactive material. However, its poor chemical stability and cytocompatibility limits its biological applications. The aim of this study is to incorporate Titanium (Ti) into CaSiO3 to produce a ceramic with improved chemical stability and biological properties. Sphene (CaTiSiO5) ceramics were prepared by sintering sol-gel-derived CaTiSiO5 powder compacts and their chemical stability was assessed by measuring the ions released and weight loss after soaking CaTiSiO5 in simulating body fluid for 1, 3, 7, and 14 days. Results indicated that CaTiSiO5 has a significantly improved chemical stability, compared with CaSiO3. The ability of CaTiSiO5 ceramics to support human bone-derived cells (HBDC) attachment, proliferation, and differentiation was assessed using scanning electron microscopy, MTS, and alkaline phosphatase activity assays, respectively. CaTiSiO5 ceramics supported HBDC attachment and significantly enhanced their proliferation and differentiation, compared with CaSiO3 ceramics. Taken together, this study demonstrates that the newly developed CaTiSiO5; ceramics possess excellent chemical stability and bioactivity, suggesting their potential use in skeletal tissue regeneration and as coating onto currently available orthopedic/dental implants. (C) 2007 Wiley Periodicals, Inc.