Different lanthanum conversion films coated directly on zinc particles are prepared by ultrasonic impregnation with the variable concentration of lanthanum nitrate solution and the adjusted ultrasonic time to modify zinc powder, and the characterization as well as electrochemical behavior of zinc are analyzed using scanning electron microscopy, energy dispersion spectrometry, potentiodynamic polarization, cyclic voltammetry. The lanthanum conversion films are found to enhance the property of corrosion resistance, suppress the dendritic growth and reduce the capacity loss for zinc electrode made of such modified zinc powder. Furthermore, the particle size of zinc powder immersed in lanthanum nitrate solution becomes thin and slim under the effect of ultrasound, which is beneficial to improve the electrochemical reaction activity of zinc powder at the assurance of high corrosion resistance for zinc electrode. (C) 2007 Elsevier B.V. All rights reserved.