Solvent-polymer and solvent-clay interactions are very important in determining the properties of polymer-clay nanocomposites. In the present work, hydrogenated nitrile rubber-sepiolite nanocomposites were prepared and the interaction parameters of various solvents with rubber (chi(AB)) and clay (chi(CD)) were studied. Nine different sets of solvent combination were chosen based on their solubility parameter. A correlation between thermal, mechanical and optical transmittance properties of polymer-clay nanocomposites and the difference in their interaction parameters with various solvents (chi(AB) - chi(CD)) was analyzed for the first time. This study helped to identify chloroform/methyl ethyl ketone as the best solvent combination, where temperature at which maximum degradation of the polymer took place was raised by 65 degrees C and tensile strength and modulus at 100% elongation were enhanced by almost 200% over the neat rubber. The results were correlated with the data of X-Ray Diffraction study, Atomic Force Microscopy and Transmission Electron Microscopy. Finally, thermodynamic interpretation was made to explain the results. (C) 2008 Elsevier Ltd. All rights reserved.