Nanowires composed of antimony, gold, and bismuth telluride (Bi2Te3) were reduced in diameter by electrooxidation in aqueous solutions. When electrooxidation was carried out using low current densities (J(ox) < 150 mu A cm(-2)), the mean wire diameter decreased in direct proportion to the oxidation time, as expected for a kinetically controlled process. Under these conditions, the diameter uniformity of nanowires remained constant as wires were shrunk from initial diameters of more than 120 nm to less than 40 nm, for Sb and Bi2Te3, and less than 60 nm for Au. Oxidized nanowires remained continuous for more than 100 mu m. Electrooxidation at higher current densities rapidly introduced breaks into these nanowires. Electrochemical wire growth and shrinking by electrooxidation were integrated into a single electrochemical experiment that allowed the final mean diameter of nanowires to be specified with a precision of 5-10 nm.