A novel reversible addition-fragmentation transfer (RAFT) agent was successfully prepared using aminopropyl-isobutyl polyhedral oligomeric silsesquioxane (POSS). The POSS-containing RAFT agent was successively applied in the RAFT polymerization of styrene to produce the organic/inorganic hybrid homopolymer and block copolymers. The polymerization results showed the POSS-containing RAFT agent is an effective chain transfer agent (CTA) in the RAFT polymerization of styrene. The thermal properties of the organic/inorganic hybrid polymers were also investigated by differential scanning calorimetric (DSC) and thermal gravity analysis (TGA). The results displayed the thermal properties of the hybrid polystyrenes are effectively enhanced by POSS molecules. (C) 2008 Elsevier Ltd. All rights reserved.