Due to pollution issue and dark color of carbon black, nonblack filler are getting more importance for reinforcing elastomer. EPDM-kaolin composites with variable maleated EPDM concentration have been prepared by mixing on a two roll mill. Optimum cure time increases with increasing compatibilizer concentration without decreasing torque value indicating that acidic functional groups comes from compatibilizer could retard cure rate and increase optimum cure time rather than change in ultimate cure state. As the concentration of filler increases, the edge to edge and face to edge interaction between filler and EPDM increases and the free volume between EPDM molecules is reduced, leading to less solvent swelling increasing crosslinking density. The results obtained shows that with increasing filler concentration the modulus and elongation at break increases due to the intertubular diffusion of EPDM inside the clay. The morphological study revealed that homogeneity of filler dispersion increases with increase in compatibilizer concentration which support the results obtained from tensile test. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119:2268-2274, 2011