A general procedure for the epoxidation of various olefins using hydrogen peroxide as the oxidant in the presence of ruthenium trichloride has been developed. Aromatic and aliphatic olefins gave the corresponding epoxides at room temperature in good to excellent yield. For turnover numbers (TON) up to 16,000 the key factor for obtaining high yield and chemo selectivity is the use of pyridine-2,6-dicarboxylic acid (pydic) as ligand. (C) 2004 Elsevier B.V. All rights reserved.