Lithium is a light metal which is nowadays very important for applications, in particular in the energy domain. Thus, characterization and quantification of lithium, that is to say determination of the chemical state, location and number of Li atoms in a sample, is important. If x-ray spectroscopy of lithium can be implemented efficiently in scanning electron microscopes (SEM) or electron microprobe analyzers (EPMA), then one could expect to use the standard processes and quantification tools to determine the weight fraction of lithium in solid samples. Thus, SEM and EPMA could be used at all the stages of the production and use of lithium, from the characterization of geologic samples and to battery devices. The atomic number of lithium is three, thus its electronic structure is very simple: two 1s electrons and one valence electron with n=2 principal quantum number. In consequence the Li x-ray spectrum is also quite simple: it consists in the K emission band corresponding to the 2p – 1s electron transition. Following the low binding energy of the Li 1s core level, the Li K emission band lies in the ultra-soft x-ray or extreme ultraviolet spectral range, at photon energies around 50 eV. However, despite the development of new dispersive elements, the spectroscopy of lithium is still a difficult task on SEM and EPMA. First, in the ultra-soft x-range there is no transparent materials. The strong attenuation of the radiation makes the analyzed thickness quite shallow, from a few nanometers to some tens of nanometers, so that few lithium atoms contribute to the emission. In addition, the Li 1s fluorescence yield is extremely low, leading to a quite low emitted intensity. Regarding the possible quantification, attenuation coefficients are not well known. Moreover, Li K being an emission band the position of its maximum and its shape depend on the chemical state of the emitting lithium atom. So, standard process relying on the determination of the intensities from the height of the considered emission cannot be used. Second, from the experimental point of view, any window in the spectrometer will lead to a strong loss of photons. Owing to the long wavelength, crystals can be used to disperse the radiation. Thus, periodic multilayers or gratings must be used, both having limited reflectance. In both cases, the used spectrometer will have a small solid angle of collection, making necessary to use large incident electron currents, of the order of a few hundreds of nA, in the SEM and EPMA. This is not harmless, because thus currents focused in small spots can lead to the damaging of the sample or to the migration of the lithium atoms. We shall review the different points mentioned above.