Résumé : The equilibrium constant for the hydrogen‐bond association aromatic base + methanol ⇋ complex in carbon tetrachloride has been determined by I.R. spectroscopy. The compounds examined are (K in 1.mole−1): pyridine 3,1, quinoline 3,5, isoquinoline 3,8, 1‐azaphenanthrene 4,7, 2‐azaphenanthrene 3,9, 4‐azaphenanthrene 1,6, 9‐azaphenanthrene 4,7, 9‐azaanthracene [acridine] 4,9, 1‐azafluoranthene 3,3 and 7‐azafluoranthene (4,5). The low value found for 4‐azaphenanthrene is attributed to steric hindrance. The other values are much too close together to allow any interpretation on the basis of electronic charges calculated by LCAO. Copyright © 1963 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim