A modified Wenzel model was proposed to explore the influence of pore size distributions (PSDs) on water repellency of nanostructured surfaces. Rough surfaces with different porous structures, including surface areas and PSDs, were fabricated by stacking different solid ratios of TiO2 nanoparticies. These fluorinated surfaces exhibited an excellent hydrophobic performance with the highest value of contact angle similar to 165 degrees. The PSDs of these surfaces, determined from Dubinin-Stoeckli equation, were found to vary with the solid ratios. The modified Wenzel model incorporated with the PSDs gave a fairly good prediction in describing the variation of contact angle with surface roughness, which is very close to the experimental data. These results demonstrated that the heterogeneity of surfaces caused by different PSDs would induce the hydrophobic behavior. (c) 2006 Elsevier B.V All rights reserved.