Polybenzoxazine-polydimethylsiloxane (PBa-PDMS) hybrids were successfully prepared in situ by the ring-opening polymerization of benzoxazine (Ba) and the sol-gel process of diethoxydimethylsilane (DEDMS). The reaction conditions were optimized, and homogeneous opaque hybrid films were obtained up to 13 wt% of PDMS content by using p-toluenesulfonic acid as the catalyst for sol-gel process. The domain size of PDMS in the PBa matrix was examined by SEM. The tensile strength and elongation at break of the PBa-PDMS hybrid films were higher than those of pristine PBa, because of the toughening effect of PDMS. Dynamic viscoelastic analysis showed that the glass transition temperature of the hybrid was also higher than that of pristine PBa. Moreover, the decomposition temperatures and weight residue at 850 degrees C increased with the increase of PDMS content as evidenced by thermogravimetric analysis. (C) 2008 Elsevier Ltd. All rights reserved.