Geometric properties of gas/liquid/solid three-phase boundary (TPB) zones of dispersive liquid on a metal surface in soils, play an important role in the cathodic and corrosion behavior of metals. The correlation between the TPB geometric parameters (e.g. its length and width) and the soil water content is established, and on this basis, the influence of TPB parameters on the cathodic oxygen reduction process of soil corrosion is simulated. The simulation result shows an initial increase and a subsequent decrease in cathodic limiting current with increasing soil water content, and a maximum is present at about 60% water content of their water holding capacity (WHC), in good agreement with the experimental results. In addition, a parameter b is proposed to evaluate the liquid dispersion in soils, and a linear dependence of cathodic limiting current on parameter b is calculated from the model, confirming the important role of liquid dispersion in soil corrosion systems. (C) 2009 Elsevier Ltd. All rights reserved.