A model of a liquid-phase membrane reactor is presented here. The model utilizes a reaction scheme and rate data applicable to the hydrocracking of California Hondo crude derived asphaltenes. Two reactor configurations have been investigated. In the first reactor configuration (configuration A) the shell-side reactor volume is kept constant by continuously pumping into the reactor pure solvent. In the second reactor configuration (configuration B) no additional solvent is added to the reactor shell side, whose volume, as a result, decreases as the solvent and solutes diffuse across the membrane from the shell side to the tube side. The model has been utilized to identify optimal reactor and process conditions and membrane characteristics, which maximize conversion and product yields.