Electronically conducting polythiophenes functionalized with methacrylate side chains have been synthesized and characterized. irradiation with UV-visible light leads to photochemical crosslinking and insolubilization of the polymer films. The minimum gel dose required to leave an insoluble residue for poly[3-(2-(methacryloyloxy)ethyl)thiophene-co-3-hexylthiophene] was 2.6 mJ cm(-2) and the dose required to obtain 50% insolubilization was 24 mJ cm(-2). Films of the homopolymer, poly(3-(2-(methacryloyloxy)ethyl)thiophene), were Lithographically more sensitive than the copolymer as indicated by the lower gel dose (1.2 mJ cm(-2)) and lower dose required for 50% insolubilization (13.4 mJ cm(-2)). Polymer films were imaged by conventional semiconductor photolithography. Patterned images were obtained having film thicknesses of 75 nm and a resolution of 3 mu m. Films doped with gold trichloride achieved conductivities up to 12 S cm(-1).