Curing dynamics and network formation of cyanate ester resin (PT-30)/TriSilanolPhenyl polyhedral oligomeric silsesquioxane (POSS) nanocomposites were studied by means of differential scanning calorimetry (DSC), modulated temperature differential scanning calorimetry MTDSC), Fourier transform infrared (FTIR) and Raman spectroscopies. The incorporation of the POSS showed a strong catalytic effect (decrease in curing temperature and activation energy) on the curing reaction of PT-30. The activation energy of the PT-30 decreased with increasing POSS content The most effective catalytic effect was observed at 5 wt% of the POSS. Both FTIR and Raman spectra monitored the formation of triazine (i.e. cyanurate) ring in the PT-30 and its nanocomposites with the POSS. Raman spectra revealed that the PT-30 resin preferentially reacted with OH group in the POSS firstly to form a -O-(C=NH)-O- bond, rather than react with itself to form the triazine rings, during the network formation of the PT-30/POSS nanocomposites. The strong catalytic effect of the POSS on the curing process of the PT-30 appears to be due to the formation of this -O-(C=NH)-O- bond. (C) 2011 Elsevier Ltd. All rights reserved.