The Regular Regime analysis, introduced by Schoeber in 1976, enables the determination of concentration dependent diffusivities from a single desorption experiment. A study on theoretical and practical aspects of this analysis is presented here. The theoretical background of the method is treated. Efforts have been made to simplify the calculation procedures by compacting and clarifying some complicated relationships. The calculation has become simple, straightforward and easy to use in practice. A stepwise procedure is given.