Cumene hydroperoxide degradation in chlorobenzene in the presence of zinc naphthenate was studied. It was found and kinetically corroborated that the degradation is preceded by the formation of an intermediate complex of the hydroperoxide with the catalyst monomeric form. The kinetic and thermodynamic parameters of the complex are close to those recently found for zinc 2-ethylhexanoate. A procedure for the calculation of the concentration of the catalyst monomeric form from kinetic data is proposed.