In this paper, it was found that the electrocatalytic activity of a Pt electrode for the electro-oxidation of formic acid could be dramatically enhanced with the modification of macrocycle compounds, such as iron-tetrasulfophthalocyanine (FeTSPc). The electro-oxidation of formic acid on a modified Pt electrode with FeTSPc occurs mainly through a direct pathway. A series of macrocycle compounds were also investigated as modifiers and exhibited a promotion effect similar to the Pt electrode. Therefore, platinum-macrocycle co-catalysts can promote the electro-oxidation of formic acid through a highly effective route, and are potential catalyst materials for a direct formic acid fuel cell (DFAFC). (C) 2008 Published by Elsevier B.V.