Sr-hexaferrites prepared by co-precipitation method and calcined at 700-1000 degrees C have been characterized by thermogravimetric and differential thermal analysis (TG-DTA), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H(2)-TPR), and Ar adsorption techniques. It has been shown that hexaferrite phase formed after calcination at 700 degrees C is amorphous and its crystallization occurs at 800 degrees C. Specific surface area (S(BET)) of the samples calcined at 700 degrees C is 30-60 m(2)/g. Reduction in hydrogen proceeds in several steps, Fe(III) in the hexaferrite structure being practically reduced to Fe(0). Amount of hydrogen necessary for the reduction of the samples decrease in the order: SrMn(2)Fe(10)O(19)>SrFe(12)O(19) > SrMn(6)Fe(6)O(19) > SrMn(2)Al(10)O(19). Surface composition of the ferrites differs from bulk. According to XPS data, the surface is enriched with strontium. Sr segregation is most probably explained by the formation of surface carbonates and hydroxocarbonates. The main components on the surface are in oxidized states: Mn(3+) and Fe(3+). Maximum activity in the methane oxidation is achieved for the SrMn(x)Fe(12) (x)O(19) (0 <= x <= 2) catalysts. These samples are characterized by highest amount of the hexaferrite phase, which promotes change of oxidation state Mn(Fe)(3+) <-> MMn(Fe)(2+). (C) 2010 Elsevier Ltd. All rights reserved.