Polyimide-MMT (montmorillonite) nanocomposites has been prepared by melt blending an organo-modified MMT with a thermoplastic poly(etherimide) (PEI) in an internal mixer. The dispersion of the MMT layers within the PEI matrix was verified using X-ray diffraction and transmission electron microscopy, revealing an exfoliation morphology. Owing to the molecular dispersion of the MMT layers and the strong interaction between PEI and MMT, the nanocomposites exhibited a substantial increase at glass transition temperature and thermal decomposition temperature, and a dramatic decrease in solvent uptake compared to the virgin PEI.