This work uses infrared absorption spectroscopy to study the organic acid dimers (CH3(CH2)(6)COOH)(2), (CH3(CH2)(7)COOH)(2), (CH3(CH2)(8)COOH)(2), and their monomers. There is a scarce literature base about these acids and the dimers have not been previously studied in gas phase. Ab initio calculations of vibrational harmonic frequencies are used as a guide for spectroscopic investigations of C=O and O-H stretching regions. Correlation between experiment and theory as well as an interesting trend with acid chain length are discussed. D-o and D-e are calculated for all dimers using the B3LYP/6-311++G[3df,3pd] method and are compared to literature values for short chain organic acid dimers. (C) 2004 Published by Elsevier B.V.