Two types of ionic liquids (IL), i.e., molecular ionic 1-butyl-3-methylimidazolium thiocyanate ([BMIM]SCN) and deep eutectic solvent (DES) based on choline chloride and tris(hydroxymethyl)propane, as well as their mixture have been used as epoxy resin curing agents. [BMIM]SCN showed the highest catalytic activity toward epoxy resin polymerization as compared to up today used ILs. Curing process of epoxy resin was investigated at ambient temperature (storage time up to more than 60 days) and elevated temperatures (80–200°C) using rheometry and DSC techniques. Thermomechanical analysis allowed to determine an influence of IL type and content on composites crosslinking density, glass transition temperature, and tan δ values. Graphite nanoplatelets (GNP) was dispersed in DES and then in DES/IL/epoxy resin composition prepared, cast, and cured to obtain nanocomposite material. Electrical volume resistivity of the nanocomposites with 0.25–1 wt % GNP increased with nanofiller content up to the highest value of 2.8 × 106 Ω · cm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40401.