Butyl rubberstrontium cerium titanate (BS) composites have been prepared by hot pressing. The tensile tests show that the BS composites are flexible. The dielectric properties of the composites have been investigated at 1 MHz and 5 GHz as a function of ceramic contents. The composite with volume fraction 0.43 of ceramic filler has a dielectric constant (er) of 11.9 and dielectric loss (tan d) 1.8 x 10(-3) at 5 GHz. The measured values of er are compared with the effective values calculated using different theoretical models. The thermal conductivity of the composites is found to increase with ceramic contents and reaches a value of 4.5 Wm-1 K-1 for maximum filler loading 0.43 volume fraction. The coefficient of thermal expansion of the composites decreases gradually with filler loading and reaches a minimum value of 30.2 ppm degrees C-1 at a volume fraction 0.43. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012