Quasi-fullerenes (Cn-q, where q stands for quasi) are novel molecules that exhibit geometries such as carbon cages with interesting electronic structure properties due to the diversity on the shape of the rings in their structure. In this work, we studied the structural stability and electronic structure properties of possible endohedral metallo quasi-fullerenes M@Cn-q (M = Sc, Ti, V, Cr; n = 42, 48 and 60). These systems have been systematically investigated using density functional theory calculations. We calculated binding energies with the zero-point energy correction to determine the stability of these new endohedral compounds. We found that the bond between Sc with the carbon cages is mostly covalent. Moreover, all metals transferred charge to the cage. The stability and reactivity were also evaluated with the following criteria: hardness (η), chemical potential (μ) and HOMO–LUMO gaps (ΔEHOMO-LUMO). The charge distributions were studied with NBO population analysis, molecular electrostatic potential isosurfaces and electron localization functions. The cage aromaticity was evaluated in accordance to nuclear independent chemical shift methodology, and it was disclosed that the insertion of these metals increased aromaticity, showing that this property may play a crucial role in the stabilization of the endohedral species. We also studied thermal stability for the Sc@Cn-q series with Lagrangian molecular dynamics using Atom Center Density Matrix Propagation method. This work may aid to understand the possibility to determine the formation of new carbon cages with the ability to trap metal atoms.