This article is a selective review where we present our model approach to study electrocatalytic reactions using layers of vertically aligned carbon nanofilaments catalyzed with Pt nanoparticles (Pt/VACNF). Featuring well defined 3D ordered architectures, these layers offer well defined mass transport conditions to the surfaces of catalytic particles, and thus are well adapted for performing combined experimental and kinetic modeling studies. Investigation of the hydrogen oxidation and the oxygen reduction reaction on Pt/VACNF provides valuable information on the dependence of the catalyst utilization (HOR, ORR) and product selectivity in multistep electrochemical reactions (ORR) on the electrode structure. The last part of the review is devoted to the study of a reaction with complex non-linear behavior, the CO bulk oxidation. Here a new (compared to 20 electrodes) phenomenon is demonstrated: the formation of the CO coverage pattern along the nanofiber length. 3D-ordered catalytic layers will be compared with 2D systems, as well as with conventional thin and porous layer approaches widely applied to studies of fuel cell electrocatalysts. (C) 2012 Elsevier Ltd. All rights reserved.