AbstractYields and cation‐exchange capacities for Ca and Cu were determined for lignin samples isolated with 72% H2SO4, HCl‐H3PO4 mixture, 5% aqueous NaOH, and 1,4‐dioxane. Yields varied with extractant in the order: acid‐ > dioxane‐ > NaOH‐extracted lignins. For equal time, a higher yield of dioxane pine lignin was obtained by fractional than by a one‐step extraction. In most cases cation‐exchange capacities varied with lignin source and with method of extraction as follows: (a) Straw lignins > wood lignins; (b) alkali‐ > dioxane‐ > acid‐extracted lignins.Lignins isolated by fractional extraction with dioxane showed the later fractions to have higher exchange capacities. Values for the one‐step extracted isolates were intermediate with respect to the high and low values of the fractionally isolated samples. Lignin, like soil organic matter, had higher adsorptive capacity for Cu than for Ca, and the adsorptive capacity was pH dependent. All samples examined for the effect of pH on Cu adsorption showed the same relative change in adsorption for a given change in solution acidity.