A novel process of morphological evolution was observed on a polycrystalline platinum electrode surface during intensive potential perturbation in sulfuric acid electrolyte. The process was started from a smooth polycrystalline platinum surface, and ended up with a roughened overlayer which is composed of numerous morphological units. According to its appearance, the unit is named "feather-like morphology (FLM)" which contains finer structures at nanometer scale. The active surface area of platinum at different stages during the morphological evolution was estimated by cyclic voltammetry. Electron microscopic measurements provided both morphological details and crystallographic information. (C) 2007 Elsevier Ltd. All rights reserved.