CrxSiBEA catalysts (x = 0.2, 1.0, and 3.4 Cr wt %) are prepared by a two-step postsynthesis method. The introduction of Cr ions in the framework of dealuminated SiBEA zeolite evidenced by XRD generates Bronsted acidic sites as shown by FTIR of pyridine used as molecular probe. In CrxSiBEA as prepared, chromium is mainly present as octahedral Cr(III) and in calcined CrxSiBEA (773 K, 3 h, flowing air) as distorted tetrahedral Cr(VI), as evidenced by DR UV−vis, TPR, and XPS. Upon outgassing of calcined CrxSiBEA at 773 K for 1 h (10−3 Pa), part of Cr(VI) is reduced to distorted tetrahedral Cr(V), as shown by EPR. Isolated distorted tetrahedral Cr sites present in activated CrxSiBEA are responsible for their catalytic activity in the oxidative dehydrogenation (ODH) of propane, performed in the presence of air or N2O. The propane conversion increases with Cr content in the presence of air or N2O, while the selectivity toward propene depends on the reaction temperature and oxidant. In the presence of air, the se...