An investigation was carried out to quantify the impact on insulation properties of room temperature vulcanized silicone rubber material when adding selected nanofillers, such as Silica, ATH and their combinations. In particular, the hydrophobic surface properties of the material are examined in details. Static, advancing and receding angles were measured under unpolluted conditions. The effect on material properties of salt deposit densities and non-soluble material deposit densities of the surface pollution layer were evaluated for all test samples. The results obtained in this work provide an initial indication of what may constitute suitable percentage levels and best nanofiller combinations to be adopted in future investigations and possible applications. © 2016 IEEE.