Abstract The air-cathode of microbial fuel cells provides an approach of zero energy consumption to supply with the cost-free source of electron donors for energy recovery from wastewater. The catalyst layer (CL) is the place where oxygen reduction reactions (ORRs) happen, which mainly determines the performance of the air-cathode. In this review, we discuss the CL toward future application based on the overview of the air-cathode structure, the ORR catalyst, the binder, and the biofouling. Both bottlenecks and possible solutions are also interpreted.