The kinetics and thermodynamics of the liquid phase isomerization of an alpha- and beta-pinene mixture oil a Pd/C catalyst were studied. The effects of pinene concentration, catalyst particle size, stirring rate, reaction temperature (293 423 K) and hydrogen pressure (0.5 - 11 bar) on the rate of alpha- and beta-pinene isomerization were investigated. The reaction rate of the alpha-pinene isomerization has the first order with respect to the alpha-pinene concentration and 0.5 order with respect to the hydrogen pressure. The thermodynamic parameters of the isomerization (Gibbs energy, reaction enthalpy and reaction entropy) and the equilibrium ratio of pinenes under the conditions studied were determined. The general scheme of the reaction mechanism of alpha- and beta-pinene isomerization over the Pd/C catalyst was proposed.