Behaviour of oxalic, citric, succinic, and maleic acids at the air/water interface is characterized and quantified by surface tension measurements in a broad concentration range and molecular dynamics simulations in slab geometry employing a polarizable force field. The relative order of surface propensities of these atmospherically relevant acids is established in this study with results being also in a very good agreement with previous measurements. (c) 2008 Elsevier B. V. All rights reserved.