The biodegradation of benzothiazole and 2-hydroxybenzothiazole by two strains of Rhodococcus was monitored by reversed phase high-pressure liquid chromatography and by 1 H nuclear magnetic resonance (NMR). Both xenobiotics were biotransformed into a hydroxylated derivative of 2-hydroxybenzothiazole by these two strains. The chemical structure of this metabolite was determined by a new NMR methodology: long-range 1 H-15 N heteronuclear shift correlation without any previous 15 N enrichment of the compound. This powerful NMR tool allowed us to assign the metabolite structure to 2,6-dihydroxybenzothiazole.