Low strain dynamic mechanical properties reveal that carboxylated nitrile rubber undergoes physico-chemical interaction with surface oxidized carbon black when molded at high temperature (190 degrees C). The extent of interaction between rubber and filler depends on the concentration of oxygen containing functional groups on the filler surface and on molding time and temperature. In case of sulfur-vulcanized systems molding was done at a lower temperature (150 degrees C) which is responsible for the reduction in the chemical interaction between rubber and filler.