In this Letter, we report on the finding of a lower barrier height of the Wang and Bowman (WB) [D.S. Wang, J.M. Bowman, J. Chem. Phys. 101 (1994) 8646] potential energy surface (PES) for the C2H + H-2 -> C2H2 + H reaction basing on ab initio calculation at the QCISD (T, full)/aug-cc-pVTZ//QCISD (full)/cc-pVTZ level. The barrier height of the modified WB (designated as MWB) PES is 2.29 kcal/mol. The rate constants have also been calculated based on the MWB PES and the ab initio calculation in the present work by the POLYRATE version 9.1 program. The rate constants calculated from the MWB PES agree well with the experimental data as well as the ab initio results in the present work. (c) 2005 Elsevier B.V. All rights reserved.