A novel method of in situ incorporation of an ATRP initiator during synthesis of hydroxyapatite particles is described. Calcium nitrate tetrahydrate, ammonium hydrogenphosphate and 2-bromo-2-methylpropionic acid were used as the functionalized hydroxyapatite precursors. Particles with homogenous size distribution within the diameter range of 300 divided by 500 nm and controlled initiator content were synthetized. The synthetic procedure of hydroxyapatite was investigated in detail to determine the influence of numerous parameters such as pH of reaction mixture, ATRP initiator concentration, dilution of ammonium hydroxide, on the final properties of the particles. It appeared the optimal conditions were those in which reaction was carried out under basic conditions, namely pH = 10, attained by slow addition of the diluted ammonium hydroxide and using no more than 1 M initial concentration of ATRP initiator. The effectiveness of incorporated ATRP initiator was verified on the basis of surface initiated polymerization of methyl methacrylate. Particles and hybrids properties were investigated by DLS, elemental analysis, XRD, TEM, FT-IR and GPC. (C) 2015 Elsevier Ltd. All rights reserved.