Nanocomposites of modified chitosan, carboxymethyl chitosan (CMCh) with hydroxyapatite (HAP) have been prepared by coprecipitation technique. Totally three nanocomposites containing 80/20, 50/50, and 20/80 of HAP/CMCh have been prepared and were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), and scanning electron microscopy (SEM). Modified chitosan, CMCh, which is water soluble can be used for drug delivery application. TEM micrographs of the nanocomposites revealed the formation of small HAP crystallites of about 230 nrn in length and 30 nm in width that are aggregated to form elliptical shapes or morphology. TGA thermograms showed that the thermal stability of the CMCh increased with incorporation of HAP. FTIR, XRD, and XPS analysis of CMCh/HAP nanocomposites showed the peaks corresponding to CMCh as well as HAP and confirm the formation of HAP/CMCh nanocomposites. (C) 2007 Wiley Periodicals, Inc.