A systematic investigation into the surface properties of siloxane rubber/carbon black (CB) nanocomposites has been performed, using an automated scanning probe microscope. In this way the influence of CB concentration and curing rate of the siloxane rubber matrix on roughness and conductivity of the composites was studied. Decreasing the curing rate while keeping the CB concentration resulted in a decrease in both roughness and surface conductivity, which can be explained by an additional siloxane-rubber layer formed during curing.