Lanthanum cobaltate LaCoOx supported onto MCM-41 mesoporous molecular sieve was prepared by in-situ oxidative decomposition of mixed LaCo citrate complexes inside the mesopores of this support. The prepared materials were characterized by EDX, EPR and UV-Vis DRS techniques as well as by N-2-BET measurements. The nanosized LaCoOx particles within the mesopores of MCM-41 matrix contains cobalt atoms in lower than Co(III) average oxidation state. Also, the supported cobaltate does not form short-range order species of LaCoO3 but presents as the highly disordered, oxygen deficient Co oxide nanophase. Catalytic activity in MeOH oxidation was tested using both conventional fixed-bed flow system and "operando" mode of DRIFT technique. The very high activity of MCM-41 -supported cobaltate is not only due to highly dispersed LaCoO3 phase but also because of rather low oxidation state of Co. (C) 2007 Elsevier B.V. All rights reserved.