A novel porous and spherical hydroxyapatite (HA) microcomposite with an average diameter of 50-100 m was produced by suspension polymerization for the adsorption of human immunoglobulin G (IgG). The specific surface area of the pure HA and HA microcomposite were found to be 80.25 and 182.53 m(2)/g, respectively. Characterizations were performed with X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy analysis. The swelling ratio of the spherical HA microcomposites was 170%. The maximum adsorption of IgG from aqueous solution was observed at pH 7.0 (5 mM phosphate buffer) and at 45 degrees C in a batch system in which parallel separate experiments were performed independently. An IgG adsorption capacity value of up to 140 mg/g was obtained for the HA microcomposite. The IgG molecules could be repeatedly adsorbed and desorbed through the use of spherical microcomposites without a noticeable loss in the IgG adsorption capacity. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2764-2771, 2013