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.