In this paper is described a simulation technique applicable to the gel filtration of a mixture of two nonionic surfactants. The applicability was tested by using a mixture of decyl- and dodecyl-dimethylamine-N-oxides. The theoretical elution curves showed a good agreement with the experimental ones. It can be shown not only experimentally but also theoretically that the gel filtration is a powerful and convenient method to isolate the component which has a lower CMC from the mixture. © 1969 Dr. Dietrich Steinkopff Verlag.