Abstract Fuel electrode supported solid oxide cells (SOCs) have been developed on an industrial scale using the aqueous tape-casting technique. The NiO–yttria-stabilized zirconia Y₂O₃–ZrO₂ (YSZ) fuel electrode and YSZ electrolyte have been manufactured by multilayer co-laminated tape casting. Details of the tape-casting slurry formulations are described and discussed. Two types of cells were fabricated with different microstructures of the NiO–YSZ support discussed. Good electrochemical performance and stability in SOFC mode at 750 °C and 0.7 V for both button cells reaching around >0.75 W cm⁻² and with no measurable degradation after >700 h were observed. The selected cell was scaled up to large-area cells (36 cm² of the active area) and electrochemically tested at 750 °C in a single repetition unit (SRU) in SOFC (Solid Oxide Fuel Cell), SOEC (Solid Oxide Electrolysis Cell) and co-SOEC (Solid Oxide co-Electrolysis Cell) mode, and in a short-stack of two SRUs in SOFC mode. A current up to 17 A was obtained at 1.4 V (0.7 V cell⁻¹) with the short-stack configuration in SOFC mode, corresponding to ∼0.5 A cm⁻² and 24 W. The performances of the aqueous-based SOC cells can be considered highly remarkable, thus supporting the success in scaling the fabrication of SOC stacks using more environmentally friendly processes than conventional ones.