Dense and gastight dead-end tubular Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) membranes were fabricated by thermoplastic extrusion. Optimal feedstocks for the extrusion of dead-end tubular structures were obtained for a feedstock consisting of 89.83 wt% BSCF powder, 5.63 wt% ethylene vinyl acetate (EVA), 3.56 wt% paraffin wax (PW), and 0.98 wt% stearic acid (SA). Thermogravimetric analysis (TGA) was used to determine the thermal characteristics of the feedstock and to characterize the amount of binder removed during the wicking step. Straight and round dead-end tubular membranes with wall thickness of 0.5 mm could be achieved after sintering. The gastightness test showed that the membranes were leak-tight up to a pressure of 35 bar.