Films of octadecylamine molecules on mica have been prepared from ethanol solutions and characterized by atomic force microscopy. Multilayer films are formed exposing terraces with alternating frictional and wear properties, which are assigned to methyl and amino group terminations. Micellar formation in the ethanol solution and subsequent deposition onto the mica is the proposed growth mechanism. By addition of acid, the ratio between protonated and unprotonated molecules was changed. The influence of this parameter on the structure of the terraces is also reported.