A number of transition metal mixed oxides with spinel-type, corundum-type and perovskite-type structures have been prepared and characterized. Attempts have been made to improve their morphological properties and their stability. Some of them have been tested in the catalytic combustion of methane, CO and H-2 (perovskites), of propane and of phenantrene. FT-IR experiments allowed to obtain a quite complete picture of the mechanism of catalytic combustion of C3 organic compounds on spinel-type oxides MgCr2O4 and Co3O4. Nucleophilic oxygen species (lattice oxygen) is thought to be involved in both partial and total oxidation.