International audience; The properties of monolayers of the dioxan lignin and of model dehydrogenation polymers spread at the air-water interface were investigated by the following techniques: surface pressure, surface potential, ellipticity, rheological analysis and molecular modeling. Information about the state of the monolayer was obtained from Surface pressure-area and surface potential-area isotherms. At small deposited quantities (1-2 mgm(-2)) a quasi-monolayer (2D) structure is formed. The values obtained for the mean area per monomer and for the mean dipole moment Lire coherent with previously reported data. as well as with the proposed Molecular model. At higher deposited quantities (3-6 mgm(-2)) a complex 3D network is built. These statements are supported by the results obtained by means of ellipsometry and surface rheology. Ellipsometry provides data for the stability of the 2D structure and for the slightly unstable 3D network. By using an original rheological approach. both structures Lire distinguished by their mechanical response when a dilatational stress is applied. The quasi-monolayer structure behaves as in elastic 2D medium during the compression, while two relaxation processes with characteristic time of 10 and 100 s were observed. The 3D network behaves as a Maxwell viscoelastic body during, the compression. while three relaxation processes with characteristic times of 1.10 and 100 s were detected.