Microstructure evolution in rapidly solidified Al91Mn 6Fe2Mo1 ribbons after annealing was investigated using X-ray diffraction, scanning electron microscopy and analytical transmission electron microscopy including in situ heating experiment in TEM. As spun ribbons consisted of icosahedral quasicrystalline particles enriched in Fe, Mn and Mo embedded in an aluminium matrix. A small amount of quasicrystals containing Fe and Mn which coexisted with the Al3(Fe, Mn) phase was also observed between the aluminium grains. Further annealing experiments and subsequent analysis of microstructure changes in the sample showed that the quasicrystalline particles underwent a transformation into stable crystalline phases at temperatures which depended on their composition. It was observed that quasicrystals enriched in Mn and Fe transformed at much lower temperatures than primary quasicrystals with Mo content. It was noticed that two different crystalline phases formed in dependence on the temperature of annealing. The Al6(Mn, Fe) phase appeared first at the quasicrystal/matrix interface. At higher temperature, the Al12(Mn, Mo) phase formed due to reaction of the Al6(Mn, Fe) phase with the aluminium matrix. Microstructural and DSC investigations showed that addition of molybdenum improved thermal stability of the quasicrystals in Al-Mn-Fe system. © 2012 Elsevier B.V. All rights reserved.