In many cases, the mutual diffusion coefficient of organic solvents in polymeric solutions limits the drying rate during the drying process. It is known, that the concentration of the solvent in the solution has a significant influence on the diffusion coefficient. The effects of small amounts of non-volatile additives in polymeric solutions on the diffusion coefficient of the solvent are often neglected. In this work, the influence of non-volatile plasticizer triphenylphosphat on the mutual diffusion coefficient of methylenchlorid in the system methylenchlorid-triphenylphosphat-polyvinyl acetate was determined. The results showed that small amounts of plasticizer have significant influence on the mutual diffusion coefficient of solvents in polymeric coatings - especially at low solvent concentrations. (C) 2011 Elsevier B.V. All rights reserved.