Catechol O-methyltransferase (COMT) is an enzyme that plays a major role in catechol neurotransmitter deactivation. Inhibition of COMT can increase neurotransmitter levels, which provides a means of treatment for Parkinson's disease, schizophrenia and depression. COMT exists as two isozymes: a soluble cytoplasmic form (S-COMT), expressed in the liver and kidneys and a membrane-bound form (MB-COMT), found mostly in the brain. Here we report the backbone H-1, N-15 and C-13 chemical shift assignments of S-COMT in complex with S-adenosyl-l-methionine, 3,5-dinitrocatechol and Mg2+. Assignments were obtained by heteronuclear multidimensional NMR spectroscopy. In total, 97 % of all backbone resonances were assigned in the complex, with 205 out of a possible 215 residues assigned in the H-1-N-15 TROSY spectrum. Prediction of solution secondary structure from a chemical shift analysis using the TALOS+ webserver is in good agreement with published X-ray crystal structures.