We discuss the asymptotic behavior of a solute plume undergoing reversible sorption governed by a Freundlich isotherm after single‐pulse injection. Our analysis predicts that the concentration at a fixed position decays asymptotically like a power law with an exponent α = 1/(1 − n) where n is the Freundlich exponent. Correspondingly, the shape of tail is time invariant. The results are checked by comparison with numerical solutions for one‐dimensional transport in a homogeneous medium. Some further asymptotic results for this case are derived. The power law behavior provides an alternative way to derive the Freundlich n parameter from breakthrough curves in comparison to the use of inverse estimation methods. This is especially the case when evaluating breakthrough curves obtained in two‐ or three‐dimensional flow domains, for which indirect estimation of parameters becomes very difficult.