P-Cyclodextrin (P-CD) forms inclusion complexes (ICs) with adamantane-modified benzoxazines (2 benzoxazine and 3 benzoxazine). These benzoxazines can readily penetrate into the CD's hydrophobic cavity, causing turbidity of their solutions, from which fine crystalline powders are obtained. We characterized these complexes by powder X-ray diffraction, C-13 and C-13 CP/MAS NMR spectroscopies, DSC, and TGA. The X-ray diffraction and solid-state C-13 CP/MAS NMR spectroscopy indicate that the IC domains of the polypseudorotaxanes maintain their channel-type structures after the ring-opening curing reactions have occurred. Furthermore, DSC measurements indicate that complexing the adamantane-modified benzoxazine units with beta-CDs result in stiffer main chains and, thus, higher glass transition temperature. TGA also indicates that the inclusion complexes have enhanced its thermal stability. (C) 2004 Published by Elsevier Ltd.