We report a theoretical investigation of the minimum energy path for isomerization of HO3 with density functional theory (DFT). Specifically, we search for a functional that can reproduce the energy difference between the cis-and trans-isomers of HO3 which has been accurately determined in previous work. By envisaging a full-dimensional map of the isomerization path, the calculations are restricted to a cost-effective model chemistry with a medium-sized cc-pVTZ basis, with the fraction of exact exchange in one-parameter hybrids used to minimize the differences between the ab initio and DFT calculations. (C) 2014 Published by Elsevier B.V.