The preparation by post-synthesis isomorphous substitution of FeX-BEA-Y in one step was investigated for the oxidehydration of pure glycerol. TPR and DR UV–vis highlighted the presence of Fe(+III) species in the framework of zeolites. Iron allows the activation of the catalyst by the reduction by glycerol of part of Fe(+III) into Fe(+II) species, which stabilizes the glycerol conversion. Total glycerol conversion is obtained with 4wt% of iron and acrylic acid yield reaches 23% over this catalyst. The Fe(+III) tetrahedral species are thought to be the main active redox sites for the formation of acrylic acid.