In this work, TiO2 nanoparticles were immobilized on the carbon nanocapsules (CNC) treated by H2SO4/KMnO4 using a sol-gel process. The TEM images of the TiO2-coated CNC suggested that introducing crystallographic defects by acid functional groups tended to facilitate TiO2 immobilization onto the nanocapsules. The TiO2-coated CNC exhibited effective quenching on the emission of a light-emitting conjugated polymer, poly(2-phenyl-3-phenyt-4-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene) (DPO-PPV). Consequently, the composites of the TiO2-coated CNC and conjugated semiconducting polymers have potentials for photovoltaic applications. (c) 2005 Elsevier B.V. All rights reserved.