In the present work we study numerically and experimentally the CO3−xNixO4 (Spinel-like oxides) system, by means of the perturbative density functional method $(P-DFT)$; for this, we start the study from the homogeneous sample $x=0$, obtaining the main electronic properties (Band Structure ($BS$), Density of States (DOS) and Fermi surface ($FS$)), then doping ($x$) with atoms of $Ni$, in different proportions (0\%-7\% respectively), finding that as doping increases $ x\neq 0$, the forbidden gap decreases and the Fermi energy ($FE$) decreases causing the material present a transition phase for a specific doping value, all these data coincide with experimental values. Also, we found that when the system is doped, a greater number of bands are generated, which would be responsible for the phase transition. All data is compared with experimental information in all cases where experimental data is available.