The benzene ring in alkylaryl sulfonates is important in adsorption at solid-water interfaces in two distinct ways. It increases the adsorption potential by an amount equivalent to adding three CH, groups to the alkyl chain and it imparts pH insensitivity to the adsorption process. This investigation has shown that alkylbenzene sulfonate (ABS)-type surfactants adsorb in accord with the hemi-micelle hypothesis. Data on the adsorption and coagulation behaviour of commercial sodium dodecylbenzene sulfonate are also presented where, again, the hemi-micelle hypothesis provides powerful understanding of interfacial self-assembly processes. (C) 2003 Published by Elsevier B.V.