Different catalytic reactions of olefin and saturated hydrocarbon molecules, present in light naphtha require specific catalytic function(s). The relationship of these catalytic reaction(s) and surface electronic structure of different molybdenum oxidation states characterized by XPS-UPS techniques enabled us to identify the nature of the catalytic active phase in each system. Catalytic reactions of 1-pentene, cyclopentene, n-pentane, cyclopentane, 1-heptene, n-heptane and methyl cyclohexane molecules were studied on different MoO3, MoO2-x (OH) (y) and Mo(0) surfaces as a function of reaction temperatures.