The process of formation of nanosized materials with a spinel structure - aluminate and cobalt (II) ferrite - has been studied in this work. The materials obtained were characterized using X-ray phase analysis, electron microscopy, BET and Debye-Scherrer methods. It was found that the synthesized samples have a developed surface and can be used as catalysts for the decomposition of hydrogen peroxide to remove organic pollutants from an aqueous solution. Cobalt (II) ferrite exhibits increased catalytic activity in the studied process; it may be associated with the formation of the Fenton system.