The adsorption of cationic surfactant decyldimethylbenzylammonium chloride [965-32-2] by cellulose pulp was stronger and fairly const. above the crit. micellization concn. than that of anionic sodium p-octylbenzenesulfonate (I) [34309-63-2]. When I was added to unbleached pulp, solubilization occurred even at low concns. and increased with the concn. due to contaminants in the pulp. The self assocn. of the surfactants into micelles had a detg. effect on the adsorption by the cellulose fibers.