Polycarbonate (PC)/layered silicate nanocomposites were prepared by melt blending technique followed by injection molding from sodium montmorillonite (Na+-MMT) and a series of organoclay (OMMT-I, Cloisite 20A, and Cloisite15A). The effect of clay types on the mechanical, morphological, and thermal behavior of PC matrix has been investigated. The structure and morphology of the nanocomposites were determined by wide angle Xray diffraction and transmission electron microscopy. Morphological observation revealed that the organoclay platelets are best exfoliated in PC/Cloisite15A nanocomposites whereas Na+-MMT clay platelets are poorly dispersed in PC/Na+-MMT nanocomposites. Differential scanning calorimetry results showed the existence of glass transition temperature (T-g) of PC and the nanocomposites. Thermogravimetric analysis indicated that the increase in onset decomposition temperature of nanocomposites mainly depend on the type of clay and organic modifier. The effect of organoclay on the storage modulus (E'), loss modulus (E ''), and damping factor (tan 8) as a function of temperature was measured by dynamic mechanical analysis. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2101-2112, 2010