The enthalpies of solution and the molar volumes have been determined for propionamide in aqueous ethanoic acid and propionic acid solutions using a C-80 microcalori meter and a DMA60/602 densimeter. The enthalpic and volumetric interaction coefficients of propionamide with the two carboxylic acids have been evaluated. Combining the previous studies for butyramide, the pair interaction coefficients are discussed from the point of view of dipole-dipole and structural interactions and the triplet interaction coefficients are interpreted by using the solvent separated association pattern. (C) 2003 Elsevier B.V. All rights reserved.