A two-reactor catalytic system including a catalytic membrane gasification reactor and a catalytic membrane water gas shift reactor. The catalytic system, for converting biomass to hydrogen gas, features a novel gasification reactor containing both hollow fiber membranes that selectively allow O2 to permeate therethrough and a catalyst that facilitates tar reformation. Also disclosed is a process of converting biomass to H2. The process includes the steps of, among others, introducing air into a hollow fiber membrane; mixing the O2 permeating through the hollow fiber membrane and steam to react with biomass to produce syngas and tar; and reforming the tar in the presence of a catalyst to produce more syngas.