Structurally characterized tantalum-eta(2)-alkyne complexes [TaCl3(eta(2)-EtCdropCEt)L-2] (1, L-2 = 1,2-dimethoxyethane (DME); 2, L = py) acted as catalysts for the cyclotrimerization of terminal alkynes. The catalytic reaction proceeded at 25 degreesC within few hours and the trisubstituted benzenes were obtained without the formation of linear oligomers. A new tantalum complex having a terminal alkyne ligand, [TaCl3(eta(2)-Me(3)SiCdropCH)(dme)] (3), was prepared, and its catalytic performance was also investigated.