Ionic liquids (ILs) are defined as salts with melting points below 100⁰C, with many of them being liquids in a broad temperature range including the room conditions. Those low melting points are obtained by the presence of bulk, flexible and low-symmetry ions, which that the anion affects the size of Ag NPs in imidazolium-based ILs and that the anion is more likely to affect the stability of Au NPs besides changes in the cation structure can also affect the size and shape of the Au and Pt NPs. Among the several interesting properties of ILs in the synthesis of NPs, of particular interest in this work is the capacity that many ILs present to stabilize NPs and other nanomaterials like carbon nanotubes in dispersions without the use of additives like polymers, surfactants or crafted organic molecules over their surface, which are often needed in other solvents to avoid the contact and sintering between NPs. This stability cannot be attributed to a conventional electric double-layer formation around the particle, since the high concentration of ions in ILs and related solvents would result in a Debye screening length of only ca. 1 Å for the diffuse layer, resulting in a double-layer interaction too weak (if any) to compete with the van der Waals attraction between NPs. Instead, this stabilization is usually attributed to the formation of alternated layers of ions around the NPs. Those layered structures can be a result of a charge alternation, with the formation of a preferred layer of cation or anion close to the particle surface followed by a layer of the opposite ion, which was used to explain the stabilization of NPs dispersions not only in ILs but also in molten eutectic mixtures of salts composed by smaller ions like NaSCN / KSCN. This charge alternation manifests usually as a short-range structure resulting from the electro-neutrality criteria. A different kind of layered structure can be formed by the segregation between hydrophilic and hydrophobic portions of IL, where regions of low charge density, like alkyl groups, which interact mostly by weak London dispersion forces, are expelled from the contact high charge density portions of the cation and the anion which interacts by strong ionic interactions. In both cases, the superposition of solvent layers of opposing nature when two NPs get closer are appointed as the responsible for a repulsion force which leads to a stabilization of the dispersion.