Abstract Ceramic-derived components in microbial fuel cells (MFCs) aim to substitute Nafion 117. Ceramic membranes are a cheaper alternative and powders’ tailoring has beneficial flexibility for proper surface morphology, porosity, controlled permeability, and water uptake. In this work, differently from the fine fired ceramics or clay materials, barium-cerium-gadolinium oxides (BCGO) powders, co-doped with lithium (Li) or cobalt (Co), are synthesized at a low temperature and then sintered at 1400 and 1500 °C to form the ceramic surface. Results show that the pore size is always within a few microns, porosity can be varied greatly with firing temperature at fixed dwell time, and the use of Li or Co can give smooth or corrugated porous particles, respectively. The permeability tests show that the BCGO doped with Li cannot control the water flux from yeast extract-peptone- d -glucose medium (YPD) with the yeast, and the absolute amount of biofouling is higher than that of Nafion 117. BCGO doped with 5 mol% Co exhibits good permeability and lowers absolute biofouling due to the unique surface morphology of parent powders. Thus, the ceramic separators based on BCGO doped with Co can be an attractive alternative to expensive Nafion.