The electrical and thermal properties of gamma-irradiated rubberclay composites based on acrylonitrilebutadiene rubber (NBR) and styrenebutadiene rubber (SBR) have been performed. The rubberclay composites were prepared with different ratios of clay up to 50 phr using melt-mixing and hot-pressing methods. The produced sheets were exposed to gamma rays at dose levels in the range from 25 to 250 kGy. The chemical structure was studied by using FTIR technique, whereas thermal stability was tested using thermogravimetric analysis. Variations in the direct current (DC) conductivity (sigma DC) with both the clay ratio and irradiation dose were studied. The effect of the clay ratio and gamma irradiation on the dielectric constant (epsilon epsilon) and loss (epsilon) has also been investigated. The obtained results show that the thermal stability has been improved as a result of clay loading and gamma irradiation of the rubber samples. Moreover, a significant increase in the values of epsilon and epsilon with increasing both the clay ratio and the irradiation dose has been noticed. The values of epsilon epsilon for NBR samples were found to be greater than that for SBR samples. The study shows that clays could be better than ceramics for the preparation of advanced dielectric polymer composites. (c) 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E198E211, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21263