This study aims to investigate the fabrication of anode/electrolyte dual-layer hollow fiber (DLHF) with improved electrolyte properties and reduced sintering temperature for intermediate temperature solid oxide fuel cells (IT-SOFCs) via a single-step phase inversion-based co-extrusion/co-sintering technique. The sintering properties of cerium gadolinium oxide (CGO) electrolyte were studied by comparing two approaches: i) using mixed particle size electrolyte; and (ii) adding lithium oxide as sintering additive in electrolyte. When comparing the maximum power density of MT-SOFC namely nickel (Ni)-CGO/CGO (unmodified), Ni-CGO/30%nano-70%micron CGO (first approach) and Ni-CGO/lithium (Li)-CGO (second approach); it was found that the Ni-CGO/30%nano-70%micron CGO cell performed the best. At 500 degrees C, the cell produced the highest maximum power density, which was 27.5 mWcm(-2) as compared to Ni-CGO/Li-CGO cell (6 mWcm(-2)) and Ni-CGO/CGO cell (20 mWcm(-2)). The high maximum power density was attributed to the porous anode in Ni-CGO/30%nano-70%mic CGO dual layer hollow fiber which provided higher number of active reaction sites. Meanwhile, the dense electrolyte layer possessed pore filling caused by the introduction of 30% nano size CGO particles which reduced the direct flow of gases between the electrodes. The results have proven that incorporating nano size CGO and sintering additives accelerated the densification of ceria electrolyte, as well as presented an advanced electrolyte material for MT-SOFC. (C) 2018 Elsevier Ltd. All rights reserved.