Multiwalled carbon nanotubes in the form of powder or as epoxy-based masterbatch were compounded with diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin in order to evaluate the effect of the dispersion state on the main properties of the epoxy-based nanocomposites. 1-Butyl-3-methyl-imidazolium tetrafluoroborate (bmim.BF4) as ionic liquid was also employed to assist the CNT dispersion. The use of 1phr of CNT from ER-based masterbatch is beneficial for improving the dispersion of CNT, as observed by transmission electron microscopy (TEM), and the processability of the resulting system, as indicated by rheological properties. The improved dispersion also promotes an improvement of the dynamic-mechanical properties (glass transition temperature and storage modulus) as well as better adhesive properties. However, the CNT as powder displays better electrical and thermal conductivities. The presence of ionic liquid improves the electrical conductivity, but decreases the Tg and the adhesive properties. CNT also accelerates the curing process, which is also enhanced by the presence of ionic liquid. POLYM. ENG. SCI., 58:1689-1697, 2018. (c) 2017 Society of Plastics Engineers