The Ring-Hydroxylating Oxygenase database, abbreviated as “RHObase”, is a web based, manually curated and searchable database which provides comprehensive information on all biochemically studied and characterized bacterial Rieske-type RHOs. The current version of the database compiles ∼1000 entries including 196 oxygenase α-subunits, 153 oxygenases β-subunits, 92 ferredoxins and 110 reductases, distributed among 131 different bacterial strains. The proteins are linked to available PDB structures and corresponding conserved domains (and motifs). The database also includes information on more than hundred aromatic compounds and the oxygenation mechanisms followed by different RHOs implementing a total of 318 oxygenation reactions. Apart from data retrieval, there are also integrated analytical tools whereby users can also perform blast search against the database for prediction of putative substrate(s) for their query oxygenase sequence(s) or can search for potential candidate RHOs capable of transforming a desired compound.