Several kinds of (hydrogenated) nitrile elastomer ((H)NBR) compounds were prepared by melt compounding of rubbers with carbon nanotubes. Transmission electron microscopy (TEM) showed that the exfoliation degree of nanotubes was high. Multiwalled carbon nanotubes (MWCNT) were either neat or modified by hydroxyl or carboxyl groups. Morphology was also characterized by scanning electron microscopy (SEM). The cure kinetics of (H)NBR and modified multiwalled carbon nanotubes ((m-)MWCNT/(H)NBR) nanocomposites was studied. It was found that the apparent curing and over-cure activation energies (E-A and E-A,E-1) increased with the increasing amount of (m-)MWCNT. There was a less obvious change in the apparent orders of curing reactions. The results of n-th order and autocatalytic kinetic model showed that any studied content of (m-)MWCNT could increase effective thermal conductivity, but decreased the vulcanization rate of (m-)MWCNT/(H)NBR nanocomposites. Finally, the effect of (m-)MWCNT content and functionalization on tensile mechanical properties was presented. POLYM. ENG. SCI., 51:542-549, 2011. (C) 2010 Society of Plastics Engineers