Microbial electrochemical systems offer a sustainable method for the conversion of chemical energy into electrical energy or hydrogen and the production of valuable compounds, contributing to the development of a bio-based economy. This study aimed to enhance the performance of anodic bioelectrochemical systems by improving the current density of Shewanella oneidensis as a biocatalyst through strain modification and medium refinement. The genetic modification, combining the prophage deletion and overexpression of the speC gene, resulted in a 4.2-fold increase in current density compared to the wild type. Furthermore, medium refinement and incorporating riboflavin, led to an additional 5.7-fold increase in current density. The application of the modified strain and medium in a scalable microbial electrolysis cell resulted in a current density of 1.2 A m - ², similar to what was achieved previously with an S. oneidensis and Geobacter sulfurreducens co-culture, substantiating the substantial performance increase for a pure culture of S. oneidensis. Furthermore, S. oneidensis was shown to grow in medium containing up to 500 mM sodium chloride and increasing the salt concentration to 400 mM had a minor influence on growth but significantly lowered the cell voltage of the MEC system., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)