Thermal degradation behaviors of a composite constituted by poly(l-lactide) (PLA) and hydroxyapatite nanoparticle that was surface-grafted with I-lactic acid oligomer (g-HA) in a nitrogen atmosphere were studied using thermogravimetric analysis (TGA) and compared with PLA. The kinetic models and parameters of the thermal degradation of PLA and the g-HA/PLA composite were evaluated by the invariant kinetic parameters (IKP) method and Flynn-Wall-Ozawa (FWO) method based on a set of TGA data obtained at different heating rates. It was shown that the conversion functions calculated by means of the IKP method depend on a set of kinetic models. The g-HA particle slowed down the thermal degradation of PLA polymer matrix. (C) 2009 Elsevier B.V. All rights reserved.