The oxidation of formic acid on a Pt electrode is strongly catalysed by Pb, Tl, Cd and Ge adatoms. Under optimum conditions, the enhancement decreases in the order Pb>Tl>Cd>Ge. The Pb adatoms enhance the height of the peak at 0.5 V/RHE by more than 10-fold. The simultaneous underpotential deposition of Pb+Ge, Pb+Cd, Tl+Ge and Tl+Cd on a Pt electrode greatly enhances the electrocatalytic activity over that of single metal adatoms. Enhancement by binary adatoms decreases in the order Pb+Ge>Ph+Cd>Tl+Ge>Tl+Cd.