• Synthesis and characterization of nanosilica in different morphology and porosity was performed. • Non-porous curved-like and spherical and mesoporous spherical nanosilica were added to epoxy. • Cure Index was used to study the effects of amount of nanoparticles and cure condition on Cure Index. • Mesoporous-filled system had Good cure regardless of heating rate at intermediate nanoparticle content. • Cure state of epoxy/non-porous particles (Poor or Good) was additionally dependent on heating rate. An image was taken by Cure Index on curability of epoxy with silica nanoparticles having variable morphology and porosity. Three kinds of silica nanoparticles with non-porous curved-rod, non-porous spherical, and mesoporous spherical microstructures were synthesized and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM) and Brunauer–Emmett–Teller analyses. Epoxy nanocomposites containing 0.1, 0.3, 0.5 wt.% of nanoparticles cured nonisothermally in differential scanning calorimetry (DSC) at different heating rates and the glass transition temperature (T g) for fully-cured samples was estimated. Cure Index unravelled the effect of nanoparticle morphology and porosity on epoxy crosslinking. Good cure was unconditionally the case for systems containing 0.3 wt.% of mesoporous spherical nanoparticles due to appropriate dispersion of porous nanoparticles, as captured by SEM. By contrast, dependency of curing on heating rate and nanoparticle loading in the case of non-porous spherical and curved-rod particles was evidenced by partially agglomerated domains. The state of nanoparticle-polymer interaction was also inferred in view of network formation in the presence of nanosilica particles of various morphology and porosity, which was nicely monitored by the use of Cure Index. [ABSTRACT FROM AUTHOR]