The relaxation of a materially isolated nonionic surfactant solutions containing spherical and cylindrical micelles at the arbitrary heights of the first and second potential barriers of aggregation work was studied. The relaxation time was determined by the height of the first potential barrier of aggregation work and was found to be independent of the second potential barrier. It was also found that theoretically admitted small relative deviations of the concentrations of spherical and cylindrical micelles from their values in the final equilibrium state were fully measurable. It was observed that the calculated relaxation time of surfactant solutions could also be measured experimentally together with the aforementioned values.