Thermal transformations of a-pinene epoxide in composite supercritical solvents that contain CO2, lower alcohols (ethanol, isopropyl alcohol) and water were studied in the temperature range of 387-575 K at pressure 13.5-21.5 MPa. Campholenic aldehyde and carveol were shown to be the main products of alpha-pinene epoxide reactions in supercritical solvents containing water. In the absence of water, thermolysis of alpha-pinene epoxide in supercritical solvent yields campholenic aldehyde and pinocamphone, with their total amount in the reaction mixture attaining 80%. Suggestions were made on the mechanism of alpha-pinene epoxide thermal isomerization depending on acidity of supercritical solvent. (C) 2010 Elsevier B.V. All rights reserved.