Because ionic liquids (ILs) have numerous various interesting features, they are recognized as important functional reaction media and liquid materials. Several applications that take advantage of each feature have been proposed. The combination of a set of unique features, which includes negligible vapor pressure, good chemical/electrochemical stability, as well as antistatic properties, has led to the creation of some novel analytical techniques wherein the IL is used with analysis equipment that requires vacuum conditions, e.g., SEM, TEM, and XPS. In recent times, vacuum analytical techniques that employ ILs have had a significant impact on a wide variety of science and technology applications. In this chapter, recent ionic liquid-electron microscopy techniques, including associated electron-beam irradiation techniques such as energy dispersive X-ray spectrometry, electron diffraction, and ionic liquid-X-ray photoelectron spectroscopy are introduced. The former is often employed for in situ observation of electrochemical reactions in next-generation battery systems and for monitoring nanoparticle production/growth processes in ILs, and the latter can reveal IL structure at the vacuum–IL phase boundary as well as chemical/electrochemical reactions in ILs on a molecular scale.