As an effective effort in improving the performance of electrolyte/anode dual-layer hollow fibres (HFs) for micro-tubular solid oxide fuel cell (SOFC), high quality dual-layer HFs with controllable electrolyte layer thickness have been developed in this study by adjusting fabrication parameters of a single-step co-extrusion and co-sintering process. Uniform and defect-free outer electrolyte layer from 70 to 10 mu m can be achieved when the extrusion rate is reduced from 5 to 0.5 ml min(-1). Although the bending strength and the gas-tightness properties are reduced slightly with the decrease in electrolyte layer thickness, significant improvement in power output of the cell is achieved. Power density as high as 1.11 W cm(-2) is obtained on the cell with the electrolyte layer of 10 mu m in thickness, which is 114% higher than the one with an electrolyte layer of 65 mu m. (C) 2010 Elsevier B.V. All rights reserved.