Surface forces between glass beads have been investigated in aqueous hexadecyldimethylamine oxide solutions of different surfactant concentrations and upon addition of cinnamic acid or HCl. On the inward process, the long-range electrostatic repulsion between glass beads disappeared with adsorbing surfactants on glass surfaces. Instead, the weak long-range hydrophobic attraction force was observed. In the short range, the pull-in phenomenon happened at the critical micelle concentration (cmc) and below, whereas the hydration attraction force was found above the cmc. The adhesion force was observed for the outward process at the cmc and below. The patchy bilayer model was proposed for a solution above the cmc. While the hydration attraction was increased with addition of cinnamic acid, the elctrostatic repulsion was increased with increasing HCl.