Metal-respiring bacteria occupy a central position in a variety of environmentally important processes including the biogeochemical cycling of metals and carbon, biocorrosion of steel surfaces, bioremediation of radionuclide-contaminated aquifers, and electricity generation in microbial fuel cells. Metal-respiring bacteria are presented, however, with a unique physiological challenge: they are required to respire anaerobically on electron acceptors (e.g., Fe(III) oxides, elemental sulfur) that are highly insoluble at circumneutral pH and unable to enter the cell and contact inner membrane-localized respiratory systems. To overcome these physiological problems, metal-respiring bacteria are postulated to employ a variety of novel respiratory strategies not found in other bacteria, including 1) direct enzymatic reduction at the cell surface, 2) electron shuttling between the cell and metal surfaces, and 3) metal solubilization by bacterially-produced organic ligands followed by respiration of the soluble organic-metal complexes. This work highlights my latest findings on the genetic and enzymatic mechanism of metal respiration by Shewanella oneidensis, a facultative anaerobe ubiquitous to redox-stratified natural waters and sediments.