Recent studies on Mössbauer characterization of iron-containing catalysts are presented. Instrumental advances on Mössbauer measurement made possible insitu analysis of the catalysts under reactive atmospheres. With insitu Mössbauer analysis, the surface species produced via reactions with synthetic gas on iron catalysts were identified as various carbides (e.g. χ-Fe₅C₂). For iron-containing platinum-group-metal catalysts, existence of anchoring iron (III) was estimated and a schematic model for the surface structure was proposed. Good correlations between iron content and chemical states of iron in such bimetallic systems were also observed. Also introduced for their future potentiality are specific applications of Mössbauer effect, source experiment, ⁹⁹Ru Mössbauer spectroscopy, and depth-selective conversion electron Mössbauer spectroscopy which is a method for surface analysis like electron spectroscopy.