Polycarbonate (PC) nanocomposites were prepared using a melt intercalation technique with a series of organically modified clays and nano-TiO2 (nTiO2). The effect of the clay and nTiO2 loading on the morphological, mechanical and thermal behavior of the PC nanocomposites was examined. The modulus enhancement was greater for the nanocomposite formed from PC with clay than the nTiO2 nanocomposite. These nanocomposites also showed a significant decrease in tensile elongation and ductility with respect to nanoclays incorporation. The nTiO2 nanocomposites also showed superior mechanical properties to the nanocomposite reinforced with nanoclay. The experimental results were compared with theoretical models. The thermal stability of PC and its nanocomposites were investigated by thermogravimetric analysis (TGA). The glass transition temperature was examined by differential scanning calorimetry (DSC). The incorporation of C30B improved the mechanical and thermal properties up to a 5 wt% clay loading due to polar interactions between the PC matrix and the intercalant present in the C30B nanoclay. Wide angle X-ray diffraction (WAXD) showed an increase in the basal spacing of the C30B nanoclay confirming the presence of an intercalated structure. TEM confirmed the intercalation of a C30B clay layers and uniform dispersion of nTiO2 particles in the PC matrix. The viscoelastic behavior examined by dynamic mechanical analysis (DMA) under a periodic stress revealed the stiffness of the PC nanocomposite in the presence of clay and n-TiO2.