The adsorption of 2-, 3- and 4-pyridinecarboxamide (PYCA) on montmorillonite and saponite has been investigated using FIF-IR spectrometry. The intercalation of 2-, 3- or 4-pyridinecarboxamide within montmorillonite or saponite has been shown by X-ray diffraction to increase the interlayer spacings. PYCA interacted with clays by direct or indirect coordination (through water molecules) to the exchangeable cations. It is concluded that endocyclic nitrogen is mainly involved in coordination. Amido group hydrogens and oxygen, however, may involve weak H-bonding interaction with water molecules. (C) 2006 Elsevier B.V. All rights reserved.