A method for synthesis of new Ni-Mn-oxide systems is proposed. The synthesized systems have been characterised by a variety of methods including chemical analysis, infrared (IR) spectroscopy, X-ray diffraction (XRD) analysis, thermal analysis, and X-ray photoelectron spectroscopy (XPS). The results obtained reveal that the synthesized catalytic system can be successfully applied as an active phase in low temperature catalysts for complete oxidation carried out both in aqueous medium and in gas phase. The synthesis operating conditions yield hydrophilic and amorphous catalytic systems with high active oxygen (similar to8%), taking part in oxidation processes. The Ni-Mn-oxide system is characterized by high thermal stability and its composition is kept constant up to 550 degreesC. Experimental data indicate that modifying a separate Ni-oxide system with Mn one can prepare new catalytic systems with high active oxygen content, larger specific area and higher thermal stability. (C) 2003 Elsevier Science B.V. All rights reserved.