Microbial fuel cell (MFC) is a promising energy harvester for supplying sensors in seafloors where solar, thermal and vibration sources are inadequate. Extensive efforts focus improvement of MFC biological and electrochemical capabilities while the electrical perspectives are poorly developed in literature. In order to promote MFC as energy scavenger, this paper explains the methods used to electrically characterize the specific MFC for seafloor conditions and the way to model its steady state operation close to the maximum power point. The method is applied to a compost-fed MCF delivering 5.7µW at 0.14V optimal output voltage. This work is the first step to efficiently apprehend the elaboration of an electrical harvesting interface.