The interactions at the air/liquid and the liquid/solid interface have been studied for octyl ß glucoside. With the thin film balance the thickness of the equilibrium liquid films is determined as a function of surfactant concentration, inert salt concentration and pH. At high surfactant concentration and/or at low. pH black films, about 4.6 nm thick, are formed. The stabilizing forces in the black films are related to the interactions within and between the layers. The forces acting between octyl-ß-glucoside surfactant layers adsorbed on hydrophobized mica were investigated with the interferometric type surface force apparatus. The forces measured between the sugar head-groups were similar to those acting between other small nonionic groups like dimethylamine oxide and monoglycerides. However, considerably more long-range repulsions are observed between surfactants with oligoethylene oxide head-groups.