In order to study the effect of chromium ion implantation on corrosion behavior, samples of zircaloy-4 were implanted with chromium ions with fluence ranging from 1 X 10(16) to 1 X 10(17) ions/cm(2), using a metal vapor vacuum arc source operated at an extraction voltage of 40 kV. The valence states and depth distribution of elements in the surface of the samples were analyzed by X-ray photoelectron spectroscopy and auger electron spectroscopy, respectively. Transmission electron microscopy was used to examine microstructure of the chromium-implanted samples. The potentiodynarnic polarization technique was employed to evaluate the aqueous corrosion resistance of the zircaloy-4 samples in a 0.5 M H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-4 compared with that of as-received zircaloy-4 when the fluence is smaller than 5 X 10(16) ions/cm(2). The mechanism of the corrosion behavior of chromium-implanted zircaloy-4 was discussed. (C) 2003 Elsevier Ltd. All rights reserved.