An asymmetric 75 wt% Sm0.15Ce0.85O1.925-25 wt% Sm0.6Sr0.4Al0.3Fe0.7O3-delta (SDC-SSAF) dual-phase mixed ionic-electronic conducting (MIEC) oxygen-permeable membrane reactor was applied to coproduce ammonia synthesis gas (ASG, H-2/N-2 = 3) and liquid fuels synthesis gas (LFSG, H-2/CO = 2). The effects of CH4 concentration, CH4 flow rate, steam flow rate and temperature on the performance of the membrane reactor were studied. The SDC-SSAF membrane reactor showed an excellent performance for the coproduction of ASG and LFSG. An ASG production rate of 20.7 mL cm(-2) min(-1), a LFSG production rate of 51.0 mL cm(-2) min(-1) and an oxygen permeation rate of 9.1 mL cm(-2) min(-1) were achieved at 925 degrees C. Compared with traditional industrial processes, the energy saving of this membrane reactor process is expected as high as 66.5%. The post-mortem of the membrane reactor using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) characterization revealed that the membrane has an excellent structural stability under operation condition.