In this study, polycaprolactone/C-60 (PCL/C-60) hybrids were prepared via a melt-blending method. To enhance the compatibility between PCL and C-60, the acrylic acid-grafted polycaprolactone (PCL-g-AA) was first transformed to PCL-NH2 by mixing with 1,6-diaminohexane, while C-60 was oxidized using a mixture of H2SO4/HNO3 and NaOH to derive C-60 fullerol (C-60-OH). Thereafter, C-60-OH and PCL-NH2 were used to replace PCL and C-60, respectively. The resulting products were characterized using FTIR, solid-state C-13- and H-1-NMR, TGA, DMA, SEM, TEM, and Instron mechanical testing. Because of the formation of -NHCO groups through the reaction between amino groups of PCL-NH2 and hydroxyl groups of C-60-OH, thermal and mechanical properties of the PCL-NH2/C-60-OH composite were significantly superior to those of PCL/C-60. The optimal blend was the 5 wt% C-60-OH with PCL-NH2, producing an 84 degrees C increase in initial decomposition temperature (IDT). C-60-OH in excess of 5 wt% aggregated and caused separation of the organic and inorganic phases, lowering their compatibihty. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3489-3499, 2010