Composites of polyaniline in its emeraldine base form (PANI-EB) and photo-acid generators (PAG) show an increase in conductivity upon photo-irradiation due to the protonation of PANI-EB. Such materials may be utilized to fabricate conducting patterns by photo-irradiation. However, the conductivity obtained by direct irradiation of PANI-EB/PAG composites was normally quite low (<10-3 S/cm) due to aggregation of highly loaded PAG. In this work, poly(ethylene glycol) (PEG), which is a proton transfer polymer, was added to PANI-EB/PAG. Results showed that addition of low Mw (550) PEG significantly enhance the photo-induced conductivity. Conductivities as high as 10-1-100 S/cm were observed after photo-irradiation. This conductivity is comparable to that of PANI-salt synthesized by oxidizing aniline in the presence of an acid. High Mw (8000) PEG is much less effective than PEG 550, which is attributed to its lower compatibility with PANI. PEG-grafted PANI (N-PEG-PANI) was also studied as an additive. Composites of PANI-EB and N-PEG-PANI showed conductivity as high as 102 S/cm after treatment with HCl vapor. The photo-induced conductivity of the N-PEG-PANI/PANI-EB/PAG composite reached 10-2-10-1 S/cm. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013