The adsorption properties of diastereomerically pure cis-and trans-2-n-alkyl-5-methoxy-1,3-dioxanes (alkyl: n-C3H7, n-C4H9, and n-C5H11) at the air/water interface at 295 K were investigated using surface tension measurements of surface-chemically pure solutions. The surface parameters, i.e., the standard free energy of adsorption, ∆G o ad, the minimum surface area demand per molecule adsorbed, Amin, and the surface interaction parameter, H s , reveal distinct differences with respect to the molecules' stereochemistry. The adsorption parameters of these compounds are compared with those of the related cis-and trans-2-n-alkyl-5-hydroxy-1,3-dioxane derivatives. The surface parameters standard free energy and surface interaction of the corresponding homologous series of the cis-and trans-2-n-alkyl-5-methoxy-1,3-dioxanes and of the cis-and trans-2-n-alkyl-5-hydroxy-1,3-dioxanes differ considerably. However, the cross-sectional areas of the two cis and trans homologous series each approach practically identical limiting values.