An efficient method for CuCl-catalyzed homocoupling reaction of terminal alkynes in the synthesis of symmetric 1,3-diynes has been developed in supercritical CO2 (ScCO2) without organic solvent. Homocoupling of various terminal alkynes (solid or liquid) could afford the corresponding products in moderate to excellent yields. In addition, ScCO2 play the role of reactive solvent, and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) acts as the key additive for homocoupling reactions of terminal alkynes, which enhanced the reaction rate and the solubility of copper(l) catalyst in ScCO2. (C) 2014 Elsevier B.V. All rights reserved.