Display omitted ► The addition of dansyl derivatives modifies the morphology of chitosan-based films. ► Wetting properties of chitosan films are strongly sensitive to the pulsed UV laser. ► The dansyl immobilization in chitosan backbone reduces the film photostability. ► UV irradiation enhances the surface energy of films even below the ablation threshold. The morphological and wetting properties of chitosan films containing dansyl derivatives have been investigated. By means of dynamic contact angle measurements, we study the modification of surface properties of chitosan-based films due to UV irradiation. The results were analyzed in the light of the molecular-kinetic theory which describes the wetting phenomena in terms of the statistical dynamics for the displacement of liquid molecules in a solid substrate. Our results show that the immobilization of dansyl groups in the chitosan backbone leads to a pronounced enhancement of the UV sensitivity of polymeric films.