Thermal isomerization of beta-pinene and equimolar mixture of alpha-and beta-pinenes in supercritical ethanol was studied experimentally. The reactivity of structurally similar alpha- and beta-pinenes were compared in the same supercritical solvent. It was shown that both pinenes undergo thermal transformations independently of one another upon co-thermolysis in supercritical (SC) ethanol. Conversion of alpha-pinene yields monocyclic limonene as the main product, and beta-pinene gives acyclic beta-myrcene. This study allowed developing the first kinetic model of beta-pinene thermolysis in SC ethanol. (C) 2007 Elsevier B.V. All rights reserved.