In order to study the effect of titanium ion implantation on the aqueous corrosion behavior of zircalloy-4, specimens were implanted with titanium ions with a fluence ranging from 1 X 10(16) to 1 x 10(16) ions cm(-2), using a metal vapor vacuum arc source at an extraction voltage of 40 kV The valence state and depth distribution of the elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy and Auger electron spectroscopy, respectively. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircalloy-4 in a 1 M H2SO4 solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zircalloy-4 implanted with titanium ions. The larger the fluence, the better is the corrosion resistance of the implanted samples. Finally, the mechanism of the corrosion behavior of titanium-implanted zircalloy-4 was discussed. © 2005 Elsevier B.V. All rights reserved.