Rhodococcus sp. NCIMB 9784 accumulated 6- endo-hydroxycamphor 3 when grown on (1 R)-(+)-camphor 1 as sole carbon source. The structure of 3 has been unambiguously assigned for the first time using X-ray crystallography. A soluble cytochrome P450 hydroxylase, induced by growth on (1 R)-(+)-camphor and designated P450(camr), has been isolated from the bacterium Rhodococcus sp. NCIMB 9784. Using authentic 6- endo hydroxycamphor as standard, a cell-free system consisting of pure P450(camr) and putidaredoxin and putidaredoxin reductase from Pseudomonas putida confirmed that the enzyme hydroxylates (1 R)-(+)-camphor specifically in the 6- endoposition, in contrast to the 5- exo hydroxylation catalysed by the well-studied P450(cam) from P. putida. P450(camr) has a molecular mass of approximately 44 kDa, and a pI of 4.8.