Platinum-dendrimer hybrid nanowires were prepared by electrochemical reduction of the poly(amidoamine) (PAMAM) dendrimer-platinum(IV) complexes on carbon electrodes covered with alumina template membranes and characterized using scanning probe microscopy and transmission electron microscopy. Direct electrochemical deposition of the fourth and fifth generation dendrimer coordinated platinum ion complexes resulted in formation of well-defined nanowires. The electrochemical reduction of platinum(IV) complexes with fourth or fifth generation PAMAM dendrimers led to the formation of nanowires, due perhaps to the cross-linking of dendrimer molecules via complex formation of amine groups with platinum(IV), intermolecular interaction between dendrimer branches, and potential induced force between the electrode surface and platinum(IV)-dendrimer complexes. The nanosized platinum-dendrimer hybrid nanowires prepared electrochemically on glassy carbon electrodes displayed good catalytic activity for electrochemical reduction of oxygen and oxidation of alcohols. (C) 2003 The Electrochemical Society.