This chapter describes the unique properties of bacterial respiration under aerobic and anaerobic conditions. The major organic and inorganic compounds used as electron transport components are discussed along with the soluble and membrane-associated proteins in the respiratory process. The F-type and V-type ATPase structures associated with ATP synthesis are presented and uncoupling agents used to inhibit ATP production without interfering with electron transport are reviewed. Also discussed are unique events in bacterial respiration, reverse electron flow, proton cycling, interspecies hydrogen transfer, and extracellular electron transport. Photosynthetic systems used by aerobic and anaerobic bacteria are reviewed.