Moment equations were developed on the basis of the Einstein equation for diffusion and the random walk model to analytically determine the rate constant for the interfacial solute permeation from a bulk solvent into molecular aggregates (k(in)) and the inverse rate constant from the molecular aggregates to the bulk solvent (k(out)). The moment equations were in good agreement with those derived in a different manner. To demonstrate their effectiveness in one concrete example, the moment equations were used to analytically determine the values of k(in) and k(out) of three electrically neutral solutes, i.e. resorcinol, phenol, and nitrobenzene, from the first absolute (mu(1A)) and second central (mu(2C)) moments of their elution peaks, as measured by electrokinetic chromatography (EKC), in which the sodium dodecyl sulfate (SDS) micelles were used as a pseudostationary phase. The values of k(in) and k(out) should be determined with no chemical modifications and no physical action with the molecular aggregates because they are dynamic systems formed through weak interactions between the components. The moment analysis of the elution peak profiles measured by EKC is effective to unambiguously determine k(in), k(out), and the partition equilibrium constant (k(in)/k(out)) under appropriate experimental conditions.