A new thermodynamic scale of aromaticity is devised for a large spectrum of organic molecules using isodesmic reactions. The present scale named E-aroma quantifies aromaticity as the average stabilization of a conjugated bond in a cyclic/extended cyclic conjugated system as compared to a matching linear conjugated one. The E-aroma values showed good agreement with the HOMA, NICS0, NICS1, MESP, and ASE indices of aromaticity. E-aroma scale offers an easy way to compare the aromaticity of molecules in different categories to that of benzene. (c) 2005 Elsevier B.V. All rights reserved.