The oxidative dehydrogenation of propane to propylene with solid-phase oxygen of VOx-based-mixed-oxide catalysts is investigated. The catalysts are prepared by depositing VOx species on alkaline-oxide-modified theta-Al2O3 supports. X-ray diffraction and X-ray photoelectron spectroscopy reveal the nature and variations of the crystalline phases. The surface area, acidity, and reduction properties of the catalysts are functions of the innate properties of bare theta-Al2O3 and the characteristic properties of each alkaline oxide. The multistage reduction of VOx on mixed-oxide supports indicates the reduction of various VOx species. The catalysts are evaluated in a fluidized CREC Riser Simulator by injecting a known amount of propane at different reaction temperatures. All catalysts show excellent propane conversion and plausible selectivity to olefins. VOx on theta-Al2O3/CaO minimizes the formation of COx species, whereas VOx theta-Al2O3/BaO displays the highest olefin yields (49%).