The invention relates to: - a biphasic calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute material comprising a sintered CAP core and at least one uniform and closed epitactically grown layer of nanocrystalline HAP deposited on top of the sintered CAP core, whereby the epitactically grown nanocrystals have the same size and morphology as human bone mineral, i.e. a length of 30 to 46 nm and a width of 14 to 22 nm, - a process of preparing the above CAP/HAP bone substitute material comprising the steps of a) preparing a sintered CAP core material, b) immersing the sintered CAP core material in an aqueous solution at a temperature between 10°C and 50°C to start the transformation process of CAP to HAP whereby a uniform and closed epitactic grown layer of nanocrystalline hydroxyapatite will be formed on the CAP core material surface, the epitactically grown nanocrystals having the same size and morphology as human bone mineral, c) stopping the transformation by separating solid material from the aqueous solution at a time when a uniform and closed coating of at least one nanocrystalline layer of HAP is present but before the transformation process is finished completely, and d) optionally sterilizing the separated material coming from step c), and - the use of the above bone substitute material as implant or prosthesis for bone formation, bone regeneration, bone repair and/or bone replacement at a defect site in a human or animal.
