Poly(ethylene glycol)-grafted-multiwalled carbon nanotube (MWNT-g-PEG) was synthesized by a coupling reaction and formed inclusion complexes (ICs) after selective threading of the PEG segment of the MWNT-g-PEG through the cavities of alpha-cyclodextrins (alpha-CDs) units. The polypseudorotaxane structures of the as-obtained hydrogels were confirmed by H-1 NMR, X-ray diffraction and DSC analyses. The complexation of the PEG segments with alpha-CDs and the hydrophobic interaction between the MWNT resulted in the formation of supramolecular hybrid hydrogels with a strong network. Thermal analysis showed that the thermal stability of the hydrogel was substantially improved by up to 100 degrees C higher than that of native hydrogel. The resultant hybrid hydrogels were found to be thixotropic and reversible, and could be applied as a promising injectable drug delivery system. The mechanical strength of the hybrid hydrogels was greatly improved in comparison with that of the corresponding native hydrogels. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3145-3151,2010