Thin films of polyaniline (PANI) deposited onto different polymeric substrates are nanostructured by using "direct laser interference patterning" at room temperature and pressure in air atmosphere. Regular linelike arrays (see figure) with thicknesses up to 600 nm are fabricated and their activity is determined using different techniques. The structuring mechanisms of PANI supported in both polycarbonate and polyimide films are demonstrated using cross-sectional analyses performed with a dual-beam workstation.