A mesophilic sulfate reducer, strain ASRB2(T), was isolated with acetate as sole carbon and energy source from granular sludge of a laboratory-scale upflow anaerobic sludge bed reactor fed with acetate and sulfate. The bacterium was oval-shaped, 1.3 x 1.9-2.2 μm, non-motile and Gram-negative. Optimum growth with acetate occurred around 37 °C in freshwater medium (doubling time: 1.7-2.2 d). Enzyme studies indicated that acetate was oxidized via the carbon monoxide dehydrogenase pathway. Growth was not supported by other organic acids, such as propionate, butyrate or lactate, alcohols such as ethanol or propanol, and hydrogen or formate. Sulfite and thiosulfate were also used as electron acceptors, but sulfur and nitrate were not reduced. Phylogenetically, strain ASRB2(T) clustered with the delta subclass of the Proteobacteria. Its closest relatives were Desulfosarcina variabilis, Desulfacinum infernum and Syntrophus buswellii, Strain ASRB2(T) is described as the type strain of Desulfobacca acetoxidans gen. nov., sp. nov.