An enrichment consortium and an isolate (isolate TKW) of sulfate-reducing bacteria (SRB) have been obtained from metal-contaminated marine sediments of Tokwawan, Hong Kong SAR. These bacteria are capable of reducing highly toxic and soluble hexavalent chromium (Cr⁶⁺) enzymatically into less toxic and insoluble trivalent chromium (Cr³⁺) under anaerobic conditions. The enrichment consortium almost completely (98.5%) reduced 0.6 mM Cr⁶⁺ in 168 h and the rate of reduction was 0.5 g (Cr⁶⁺) g(protein)⁻¹h⁻¹. In comparison, with Cr⁶⁺ as the sole electron acceptor (as a surrogate for SO₄²⁻), isolate TKW reduced 94.5% of the initially added Cr⁶⁺ (0.36 mM) in 288 h, with the rate of 0.26 g (Cr⁶⁺) g(protein)⁻¹h⁻¹. Adsorption by these bacteria was not the major mechanism contributing to the transformation or removal of Cr⁶⁺. The biomass and Cr³⁺ in the cultures increased simultaneously with the reduction of Cr⁶⁺. These indigenous SRB might have potential application in bioremediation of metal contaminated sediments.