In this study, a single-step cofiring through the extrusion molding and wet-ceramic coating technique was developed to fabricate a cathode-supported microtubular cell. The cell is consisting of a (GDC) electrolyte with a NiO–GDC anode on a porous ∕GDC tube ( wall thickness and diameter). Densification of the ceria membrane (thickness ) was successful by cosintering the laminated thin electrolyte and the anode with the cathode at . Compared with that fabricated by the conventional two-step cofiring process, the cell showed an improved performance due to the increased anode sintering temperature, which leads to an improved anode∕electrolyte interfacial property. The cell having tube length fed with humidified (3% ) produced the maximum power densities of , , and , at , , and , respectively.