The invention relates to: -a biphasic calcium phosphate/hydroxyapatite (CAP/HAP) bone substitute material comprising a sintered CAP core and a closed epitactically grown layer of nanocrystalline HAP deposited on the external surface of the sintered CAP core, wherein the closed epitactically grown layer of nanocrystalline HAP deposited on the external surface of the sintered CAP core has a homogeneous coarse external surface comprising flat crystal platelets, which shows an enhanced osteogenic response, and -a process of preparation thereof comprising the steps of a)preparing a sintered CAP core material, b)immersing the sintered CAP core material in a buffer solution containing to 90 % of a short-chain aliphatic alcohol at a temperature between 10°C and 0°C to start the transformation process of CAP to HAP whereby a closed epitactically grown layer of nanocrystalline hydroxyapatite will be formed on the sintered CAP core material surface,whereby the epitactically grown nanocrystals have the same size and morphology as human bone mineral, wherein the closed epitactically grown layer of nanocrystalline HAP formed on the sintered CAP core material surface has a homogeneous coarse external surface comprising flat crystal platelets, c)stopping the transformation by separating solid material from the aqueous solution at a time when a 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).
