The co-dimerization reaction of vinylboronates with terminal alkynes, which was discovered in our group, is an efficient method for the synthesis of boryl- and borylsilylsubstituted buta-1,3-dienes. This study is a continuation of our previous and present results concerning the mechanism of this new catalytic reaction in boron chemistry. DFT calculations, as well as kinetic measurements carried out at several different temperatures in the range of 70-100 degrees C, provided rational grounds for the mechanism proposed previously on basis of stoichiometric reactions monitored by H-1 NMR. The activation energy and the rate determining step were also estimated. (C) 2014 Elsevier B.V. All rights reserved.