In the presence of pyridine as a co-catalyst, CH3ReO3 catalyses the epoxidation of terpenes such as alpha-pinene with H2O2 with minimal rearrangement of the epoxide. Pyridine is also critical to suppress isomerisation of the olefin substrate (in case of nerol, geraniol). The reaction can be directed towards selective single or double epoxidation, or in one step towards the rearranged product (e.g. from linalool to the ring-closure product linalool oxide). (C) 1998 Published by Elsevier Science Ltd. All rights reserved.