In this study, bentonite was modified with the compounds which have amine and hydroxyl functionality and obtained organobentonites were used as additive for the synthesis of rigid polyurethane foam nanocomposites (SPKN). The dispersion of clay layers into the polyurethane matrix was investigated using a small angle X-ray diffractometer. A Scanning electron microscope, a gas pycnometer, a heat flow meter and a universal test machine were used for the morphological characterization, closed cell content, thermal conductivity and compressive strength of the foams, respectively. The effects of additive type and amount on the average cell size, closed cell content, thermal conductivity, density and compressive strength of the foam were investigated. For all nanocomposites, the average cell size and the thermal conductivity were lower than those of rigid polyurethane foam (SPK), while closed cell content and density were higher. In the presence of organobentonite, the thermal conductivity of the foam was reduced by about 10%. While the compressive strength of nanocomposites containing 1% additive were higher than that of SPK, these values were generally decreased with the increasing amount of additive.