Recently it was found, that gas sensitivity of spinel ferrite transition metal oxide nanomaterials is affected not only by chemical composition and microstructure but also by faults and defects in the structure. Concentration of the point defects such as cation or oxygen vacancies can be regulated by replacing trivalent iron ion in tetrahedral site in the inverse spinel structure with divalent non-transition metal ions (Me2+), thus changing type of structure to mixed or normal. Also, cation and oxygen vacancies can be introduced or extinguished varying iron ion stoichiometry, synthesis parameters or method, as well as annealing conditions