Bi-metal modification of poly-3,4-ethylenedioxythiophene (PEDOT) layers by combining palladium and copper deposition is studied. Initial reference measurements are performed on electrodriven deposition and electroless precipitation of palladium, showing the existence of Pd nanocrystals on the PEDOT surface. It is established that by using the electrodeposition sequence - Cu (first step) - Pd (second step) only palladium remains available in the PEDOT layer. By reversing the deposition sequence - Pd (first step) - Cu (second step) a bi-metal modification of PEDOT is achieved. Depending on the parameters potential and time of the copper electroreduction the Pd nanocrystals coexist with either Cu-PEDOT-stabilized species or both Cu crystals and Cu-PEDOT-stabilized species. The voltammetric response of the modified PEDOT electrodes is tested for nitrate electroreduction in neutral solution. It is found that the bi-metal modified PEDOT shows a marked electroactivity for this reaction. (c) 2006 Elsevier Ltd. All rights reserved.