Abstract: There is disclosed an olefin metathesis process which comprises subjecting at least one olefin to a catalyst system consisting of (1) salts of the metals selected from the group of tungsten, molybdenum and chromium, said salts being halides or the reaction products of these metal halides with carboxylic acids, phenols and 1,3-diketones, (2) a material selected from the group represented by the formulae:R.sub.3-n MX.sub.nandR.sub.3 M.sub.2 X.sub.3wherein R is an alkyl radical containing from 1 to 12 carbon atoms, M is selected from the group consisting of aluminum, gallium and indium, X is a halogen from the group of fluorine, chlorine, bromine and iodine, and n equals 0, 1 or 2, and (3) a compound defined by the formula:N R.sub.1 R.sub.2 R.sub.3in which R.sub.1 and R.sub.2 are selected from the group of hydrogen, alkyl, aralkyl, aryl, alkenyl and alkaryl, R.sub.