The treatment of hypersaline wastewater (approximately 5% of the wastewater worldwide) cannot be performed by classical biological techniques. Herein the halotolerant extremophile bacteria obtained from the Great Salt Lake (Utah) were explored in single chamber microbial fuel cells with Pt-free cathodes for more than 18 days. The bacteria samples collected in two different locations of the lake (Stansbury Bay and Antelope Island) showed different electrochemical performances. The maximum achieved power output of 36 mW m−2 was from the microbial fuel cell based on the sample originated from Stansbury Bay, at a current density of 820 mA m−2. The performances throughout the long-term operation are discussed and a bioelectrochemical mechanism is proposed.