The relative activity of five surface Cr species was evaluated by selecting model catalysts. The redox aluminum-chromium-chromate(s) were found active in the formation of C1–C3 hydrocracking byproducts and coke. Initial operation of the fresh CrOx/Al2O3 catalyst at the dehydrogenation-regeneration mode caused non redox Cr3+ on α-Cr2O3 originally inactive on the fresh catalyst to be very active in the equilibrated one, likely due to the surface restructuring of unstable chromium species. A reaction chemistry pathway for the thermal conversion of mono-/poly-aluminum chromate(s) and physically deposited CrO3 into the aluminum-chromium-chromate(s) was proposed.