© 2015 The Royal Society of Chemistry. A study of the dilational surface viscoelastic properties of mixed solutions of lysozyme and denaturing agents with different chemical natures allows us to characterize the changes of protein tertiary structure in the surface layer upon adsorption at the liquid-gas interface. We show that guanidine hydrochloride (GuHCl) and urea influence the dynamic surface properties of lysozyme solutions less than the properties of previously studied solutions of bovine serum albumin and β-lactoglobulin. Although the addition of sodium polystyrene sulfonate (PSS) changes the kinetic dependencies of the surface properties and leads to the formation of large aggregates in the bulk phase, the dependencies of the dynamic surface elasticity on the surface pressure almost coincide with the results for pure lysozyme solutions thereby indicating the preservation of the adsorption layer structure. At the same time, the simultaneous addition of PSS and GuHCl to lysozyme solutions results in a s