Polycarbonate (PC)/nanosilica (nSiO2) nanocomposites were prepared by melt-blending technique, in which surfactants are used to enhance the interfacial adhesion between nSiO2 and polymer matrix. Mechanical properties demonstrate increased Young's modulus and yield strength of modified PC/nSiO2 nanocomposites when compared with PC. Increased compatibility further indicates an effective increase in thermal stability as observed from thermogravimetric analysis. Dynamic mechanical analysis point out a reduction in Tg value with increased storage modulus. The flammability characteristics of PC/nSiO2 nanocomposites were evaluated using limiting oxygen index, whereas the morphological properties are characterized by wide-angle X-ray diffraction and scanning electron microscopy. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers