During the sulfur vulkanization accelerated by thiurams and sulfenamides (CBS) isothiocyanates (ITC) are formed inevitable, Their amount increases with higher sulfur dosage significantly Prolonged vulcanization time and higher vulcanization temperature promote the emission of ITC, too, The reaction products formed during vulcanization at 180 and 210 degrees C were analyzed by gas chromatography combined with mass spectrometry. Zinc dithiocarbamates promote the formation of ITC more than the thiurams DMPTD, TMTD and TMTM, The lowest amounts of ITC were formed with DMPTD. Small changes to either the formulation or processing conditions can substantially reduce these hazardous components in fumes.