High catalytic activity for formic acid oxidation reaction (FAOR) is demonstrated in Pb modified shape-controlled Pt nanoparticles (NPs). Cyclic voltammetry is used to follow the effective modification of Pt NPsby Pb. Octahedral shaped Pt NPs (having a (111) preferential surface structure) modified by Pb are provedthe most active electrocatalyst studied towards FAOR and display a catalytic activity of c.a. 7 mA cm−2at0.5 V in 0.1 M formic acid solution. This current density represents an enhancement factor of 29.5 withrespect to the unmodified Pt NPs and this is 2.7 and 2.3 times higher than that found on Tl/100-Pt NPsand Sb/111-Pt NPs, respectively, some of the most active electrocatalysts based on adatoms modifiedPt NPs reported so far. This outstanding activity is displayed at maximum Pb coverage and also confers awide electrocatalyst stability over the entire potential range studied. FAOR is also studied using scanningelectrochemical microscopy (SECM) by the micropipette delivery/substrate collection (MD/SC) workingmode as a preliminary rapid test to identify active electrocatalysts. In particular, the remarkable activityenhancement exhibited by a Pt ultramicroelectrode (100 µm diameter) modified by Pb is rapidly imagedby SECM providing preliminary catalyst performance information. Thus, this technique emerges as asuitable and fast method to test, and in some cases quantify, catalyst activity for reactions of interest infuel cell applications.