Oxygenases are a broad class of enzymes which are important for the catabolism or recycling of organic matter in the environment., Bacterial catabolism of hydrocarbons and substituted aromatic compounds often uses dioxygenases containing a Rieske iron-sulfur cluster and a non-heme iron center. The dioxygenases have been useful in producing oxygenated materials directly, or indirectly by generating chiral synthetic intermediates. The recent availability of protein structures and gene sequences provides new opportunities for expanding the usefulness of this enzyme class.