Simulated body fluid (SBF) solutions are widely used for in vitro bioactivity tests and to coat bioinert materials with biomimetic calcium phosphates. In this study SBF solutions with varying HCO3 - content were used to precipitate hydroxy carbonated apatite (HCA) on a bioactive titanium surface. XRD as well as cross-sectional TEM analyses revealed that the biomimetically derived crystallites show a preferred growth orientation in direction of their c-axis and perpendicular to the surface of the substrate. FTIR and Raman analyses revealed that, as long as the HCO3 - concentration in the testing solutions is below 20 mmol/l, only B-type HCA precipitates. Using SBF with a HCO3 - concentration equal to human blood plasma (27 mmol/l) leads to a AB-type substitution where, in accordance with bone mineral, CO3 2- substitutes PO4 3- as well as OH-.