Addition of 5% Pt or alkali metals such as K or Cs each separately to the bifunctional MoO2-x(OH)(y) catalyst results in modification of the chemical structure of this system, especially in the case of alkali metals. A new MoO2-x(OA)(y), A=K, Cs. monofunctional structure having only metallic properties is formed. In the case of Cs for example, the Mo-OCs bond formation takes place in the course of the reduction process of MoO3 to MoO2 by hydrogen hinders the acidic BrOnsted Mo-OH formation, which usually is formed in this system. Characterization by surface XPS-UPS, ISS and FT-IR spectroscopic techniques as well as catalytic activity carried out at the same experimental conditions confirm the presence of this monofunctional MoO2-x(OCs)(y) system. On the contrary, platinum addition enhances the metallic character of the MoO2-x(OH)(y) bifunctional system in terms of slight improvement in the conversion of 1-heptene and n-heptane as well as dehydrogenation of methylcyclohexane to toluene. (C) 2012 Elsevier B.V. All rights reserved.