To simulate the corrosion of galvanized steel in a marine zone, steel rust of beta-FeOOH particles was prepared by aerial oxidation of aqueous FeCl2 solutions containing ZnCl2 and zinc rusts such as ZnO and zinc hydroxychlo ride (Zn-5(OH)(8)Cl-2 center dot H2O, ZHC). The crystallinity and particle size of beta-FeOOH were slightly decreased by adding the ZnCl2. The produced particles contained a small amount of ZnCl2, while the zinc rusts of ZnO and ZHC markedly impeded the crystallization and particle growth of beta-FeOOH. In the presence of a large amount of zinc rusts, the formation of beta-FeOOH was suppressed and gamma-FeOOH and ZHC of which the particle size was larger than that of beta-FeOOH were generated. The inhibitory effect on the formation of beta-FeOOH was on order of ZHC approximate to ZnO >> ZnCl2. The effect of zinc rusts was ascribed to the increment of solution pH by dissolution of rust particles and adsorption of Zn(II) on a precursor of beta-FeOOH particles. The adsorption of CO2 on the products was also suppressed by the addition of ZnCl2 and zinc rusts. These results imply that the beta-FeOOH rust formed on galvanized steel in a marine environment is more compact, leading to improved corrosion resistance. However, existence of a large amount of zinc rust particles inhibits the formation of a compact rust layer and lowers the ability for corrosion resistance.