We have developed different electrochemical procedures for the production of nanostructured bulk metals, catalyst particles and metal oxides with variable crystallite sizes. The crystallite size of the nanoparticles can be controlled by the variation of the physical and chemical process parameters. Efficient and inexpensive catalyst layers for polymer electrolyte fuel cells were prepared using pulsed electrodeposition (PED) and DC-plating procedures. The advantage of these techniques is the site-selective deposition of Pt and PtRu catalysts on the carbon support. Large amounts of nanostructured metal oxides with different crystallite sizes can be prepared with our EDOC process (electrochemical deposition under oxidizing conditions) which is based on the reduction of metal ions generated from the anodic dissolution of a sacrificial anode with subsequent oxidation of the formed metal clusters. For these nanomaterials we also discuss the physical properties (e.g. thermal stability, catalytic activity). (C) 2003 Elsevier Ltd. All rights reserved.