In this work cements based on α-tricalcium phosphate (α-TCP) are investigated. Results show that initial pH of the liquid phase for α-TCP based cements significantly influences crystal morphology and setting reaction. FTIR results show that CDHA formation process continues for several days, even after all α-TCP is hydrated. CDHA phase formed after hydration of α-TCP lacks characteristic [OH] groups during first 2 days. In vitro tests using osteoblast cell line (MG63) show differences between cements (after reactions in cements are complete). In vivo tests in rabbits show good compatibility and complete healing for all cements tested (initial liquid phase pH 8, 7 und 6).