The kinetics of hydroxyapatite (HAP) crystallization on polymers containing -CdropN functional group was investigated by the constant composition technique. The apparent order for the crystallization process was found to be 2 indicative of a surface diffusion control mechanism. Critical nucleus formation was confirmed by computational chemistry calculations using the PM3 method in the version 6.0 of MOPAC program package. The surface energy of the growing phase was 109 mJ m(-2). The HAP formation initiated through the interaction of Ca2+ ions with the negative end of the -CdropN bond. (C) 2003 Elsevier Science B.V. All rights reserved.