A series of molecular dynamics simulations to Study the structure of a surfactant monolayer near real Surfaces was carried out. A comparison of two different Surfaces, TiO2 and SiO2 with the same monolayer was performed. Moreover, each surface was modeled by two different approaches, the first model considers the complete structure of a TiO2 (or SiO2) wall, whereas the second model is a continuous solid wall with an effective potential. Both wall models give essentially the same monolayer configuration suggesting that the explicit form of the wall does not play a relevant role to study the structure Of surfactant monolayers close to planar surfaces. (c) 2005 Elsevier Inc. All rights reserved.