Manganese-substituted (0–100%) iron–potassium oxide (Mn–Fe–K) catalysts which are selective for dehydrogenation of ethylbenzene to styrene were prepared by the alcoxide sol–gel method. They have been characterized by XPS, BET surface area measurement and TPD studies. The differences of surface properties between the Mn–Fe–K catalysts and unsubstituted iron–potassium oxide (Fe–K) catalyst were reasonably reflected in the XPS spectrum of oxygen (O 1s) and potassium (K 2p). The XPS spectra of Mn–Fe–K catalysts based on the binding energy shifts of O 1s and K 2p bands resembled those of KFeO 2 as an active phase for the dehydrogenation of ethylbenzene. On the contrary, the unsubstituted Fe–K catalyst showed the XPS spectra including KOH and Fe 3O 4 as inactive phases. The presence of Mn ions in the catalyst matrix (γ-Fe 2O 3, MnFe 2O 4) results in stabilization of the KFeO 2 active phase, and did not affect catalytic behavior of the K-promoted iron based oxide. The maximum enhancement of catalytic activity at the optimum 20% Mn-substitution is owing to the large surface area, the minimization of carbonaceous deposition, and the retardation of pyrolysis of KFeO 2 to KOH and Fe 3O 4.