In this report, the influence of surface features in the nanoscale range on the hydrophobicity of fluoro-based polymer thin films was studied. For this purpose, poly[4,5 difluoro 2,2-bis (trifluoromethyl)-(1,3 dioxoie)-co-tetrafluoroethylene] was deposited by sol-gel spin coating technique on sputtered Cr-N interlayers with different surface structures. The wettability of the fluoro-based polymer thin film on the Cr-N interlayers was determined by dynamic contact angle measurements. It could be proved that structural changes in the nanometer range influences the contact angles and their hysteresis of low-surface energy materials. By applying fluoro-based polymer thin films on a nearly flat Si(100) wafer and a cone-like Cr-N structure with a certain roughness, the advancing contact angle for water on fluoro-based polymer thin film increased from 120 degrees to 148 degrees on the rough Cr-N interlayer. (c) 2004 Elsevier B.V. All rights reserved.