NBR, contg. 40% of -CN groups was vulcanized with Zn dibutyldithiocarbamate (I), tetramethylthiuram monosulfide (II), 2-mercaptobenzthiazol or NW-diphenylguanidine as accelerator and with ammonium salt-modified montmorillonite as filler. The best mech. properties had the vulcani-zates crosslinked with I or II The fillers enhanced the tensile strength, elongation at break by 100%, and thermal stability. The montmorillonite was intercalated and partly exfoliated by polymer chains. The accelerators did not affect the behavior of montmorillonite in the elastomer, but modified the structure of crosslinks.