Polyhedral oligomeric silsesquioxane (POSS)-cyanate ester (CE) nanocomposites have been developed by the incorporation of octafunctional maleimide POSS (OMPS) into the bisphenol-A based CE network through in situ method by thermal curing with the use of diaminodiphenylmethane (DDM) as coupling agent. The formation of nanocomposite was confirmed by Fourier transform infrared analysis. X-ray diffraction, scanning electron microscopy and transmission electron microscopy images confirm the morphology of CE/OMPS nanocomposites. The thermal and morphological properties were studied by varying different weight percentages (1, 3, 5 and 10%) of OMPS. The 5 wt.% OMPS-incorporated nanocomposite possesses higher values of glass transition temperature than those of nanocomposites filled with a lower percentages of OMPS. Further thermal stability of nanocomposites increased with increase in percentage composition of OMPS.