A Palladium/imidazolium chloride system has been used to mediate the dimerization of terminal alkynes to enynes. The combination of 1 mol % Pd(OAc)(2) and 2 mol % IMes.HCl in the presence Of CS2CO3 as base shows high activity and high regio- and steroselectivity for the dimerization of aryl and aliphatic terminal alkynes to enynes.