Bismuth-modified Pt nanoparticles supported on carbon have been employed as anode electrocatalyst for a direct formic acid fuel cell (DFAFC). Two different types of electrodes were used: a thin layer Pt/C working electrode deposited on a gold substrate and a coated catalyst (Pt/C) membrane. Bismuth was deposited on the Pt nanoparticles by irreversible adatom adsorption from a Bi3+ solution. Bi-modified thin-film working electrodes with different catalyst loadings (0.1, 0.5 and 1.0 mgpt cm(-2)) were tested for the electrooxidation of formic acid (2, 4.75 and 9 M formic acid solutions). Likewise, a Bi-modified coated catalyst membrane was used as anode in an air-breathing direct formic acid fuel cell. For this cell, polarization curves were obtained for different formic acid solutions. Independently of the type of electrodes, the presence of Bi caused a four/six fold increase of the electrooxidation currents as compared to unmodified Pt electrodes. Thus, the use of bismuth-modified carbon supported Pt nanoparticles is presented as an easy, feasible and versatile alternative for improving the efficiency of DFAFCs. (C) 2011 Elsevier Ltd. All rights reserved.