Abstract: The mössbauer spectra of catalysts A₆C(spherical), HAC (spherical low-temperature catalyst) and A₆ (irregular), and promoterless samples were measured by the mössbauer spectrometer AME-50.The increasing of Wustite (Fe_1-xO) content and evenness of promoters distribution (more Al⁺³ has entered into Fe₃O₄ lattice) of spherical catalysts may be derived from the particular technology of preparation by which a rapid cooling was carried out in water.There is higher Wustite content of catalyst HAC than that of A₆C for the same iron ratio. It may be derived mainly from the different amounts of Al₂O₃ in the catalysts.More Wustite in catalyst results in easy reduction and high aetivi-ty, but less thermal stability. The even distribution of promoters counteracts the later weakness and ultimately the thermal stability rises in practice.The spherical catalysts ought to have their optimum iron ratios of Fe⁺²/Fe⁺³. The catalyst HAC should be prepared with smaller iron ratio than A₆C, and the catalyst HAC can be used very well in a wide range of temperature.