The behaviour of a polyimide film with the aromatic structure during the exposure to UV light with lambda > 290 nm was studied. Significant changes in color surface and gloss surface were identified during irradiation. Sample became lighten and less glossy after exposure to the light. These modifications were correlated with the structural changes in FTIR spectra. Based on changes in FTIR spectra recorded during irradiation, a mechanism for the photochemical degradation of polyimide film was proposed. (C) 2011 Elsevier B.V. All rights reserved.