P450 monooxygenases are able to catalyse the highly regio-‐ and stereoselective oxidations of many organic molecules. However, the scale-‐up of such bio-‐oxidations remains challenging due to the often-‐low activity, level of expression and stability of P450 biocatalysts. Despite these challenges they are increasingly desirable as recombinant biocatalysts, particularly for the production of drug metabolites. Diclofenac is a widely used anti-‐inflammatory drug that is persistent in the environment along with the 4’-‐ and 5-‐hydroxy metabolites. Here we have used the self-‐sufficient P450 RhF (CYP116B2) from Rhodococcus sp. in a whole cell system to reproducibly catalyse the highly regioselective oxidation of diclofenac to 5-‐hydroxydiclofenac. The product is a human metabolite and as such is an important standard for environmental and toxicological analysis. Furthermore, access to significant quantities of 5-‐hydroxydiclofenac has allowed us to demonstrate further oxidative degradation to the toxic quinoneimine product. Our studies demonstrate the potential for gram-‐scale production of human drug metabolites through recombinant whole cell biocatalysis.