Ion evaporation is an essential step in the formation of charged ions from electrosprays, yet many aspects of the process are poorly understood. The ion evaporation kinetics of the 1-ethyl-3-methyl-imidazolium⁺ (EMI⁺) based ionic liquids (ILs) EMI-BF₄, EMI-bis(perfluoroethylsulfonyl)imide, EMI-bis(trifluoromethylsulfonyl)imide and EMI-tris(trifluoromethylsulfonyl)methide (EMI-Methide) are studied by tandem ion mobility-mass spectrometry (IMS-MS) of IL nanodrop residues from positive and negative electrosprays of IL–acetonitrile solutions. Two-dimensional (2D) IMS-MS spectra are obtained using a differential mobility analyzer (DMA) coupled to a commercial quadrupole-time-of-flight mass spectrometer. Nanodrops of different charge states (z = 1,2,…,10,…) are separated into distinct bands in 2D DMA-MS spectra, allowing for determination of both nanodrop size (radius) and charge. With the exception of negatively charged EMI-BF₄, all clusters observed are charged below the Rayleigh limit of both the ILs and acetonitrile, showing that the charge loss mechanism is ion evaporation. Solvation energies, ΔG⁰_s, of evaporating ions from acetonitrile are inferred from radius and charge state data. With the exclusion of EMI-BF₄ in negative mode (ΔG⁰_s > 1.84 eV), all are in the 1.54–1.65 eV range, considerably lower than previously reported for tetra-alkyl ammonium salts in formamide. Measured size distributions of EMI-Methide nanodrops agree with those predicted by ion evaporation theory, though with narrower widths observed for doubly and singly charged nanodrops.