The effect of anode material on the performance of microbial fuel cells (MFC), which utilise oxidisable carbon compounds and other components present in sediments on ocean floors, estuaries and other similar environments is reported. The MFC anode materials were carbon sponge, carbon cloth, carbon fibre, and reticulated vitreous carbon (RVC). Power was produced through the microbial activity at the anode in conjunction with, principally, oxygen reduction at a graphite cloth cathode. After a period of stabilisation, open circuit voltages up to 700 mV were observed for most cells. Steady state polarisations gave maximum power densities of 55 mW m(-2) using carbon sponge as the anode; which was nearly twice that achieved with carbon cloth. The latter material typically gave power densities of around 20 mW m(-2). The performance of the cell was reduced by operation at a low temperature of 5 degrees C. Generally, for cells which were capable of generating power at current densities of 100 mA m(-2) and greater, mass transport was found to limit both the anode and the cathode performance, due primarily to the low concentrations of electro-active species present or generated in cells.