The capillary wave method has been applied to aqueous solutions of sodium decyl sulfate (SDes). The damping coefficient increased monotonically with concentration below the critical micelle concentration (cmc) and decreased in the micellar region. This behavior is different from the results for solutions of sodium dodecyl sulfate (SDS), where a single local maximum of the damping had been observed at concentrations far less than the cmc. The difference can be explained with the help of the theory of surface viscoelasticity, which has been developed recently. For dilute solutions the experimental data agree with the theory based on the assumption that the adsorption kinetics is controlled by diffusion in the bulk phase. At concentrations higher than the cmc a more complex theory taking into account the micellization process has been applied. In this case the only adjustable parameter was the characteristic time of the slow stage of micellization. The values of this quantity, thus obtained from the experimental data, reasonably agree with the results of independent measurements.