A bubbling fluidized bed membrane reactor (FBMR) is modeled to estimate and predict the steam reforming of hydrocarbons. A two-phase fluidization model is used, with both the bubble and dense phases in plug flow. Diffusional mass transfer, as well as bulk convective mass flow between the phases, is incorporated to account for reactions occurring predominantly in the dense phase and increases in molar flow due to the reaction. Steam reforming of higher hydrocarbons is limited by the thermodynamic equilibrium of the methane steam reforming and water-gas shift reactions. The model predicts flexible feedstock capabilities, showing that most of the reactor does not actually see the higher hydrocarbon feed. With a single fitted constant to account for membrane effectiveness in the fluidized bed relative to that in the absence of particles, good agreement is obtained between model predictions and reactor performance of the reforming of methane, propane, and heptane.