Different investigations at Clary sage (Salvia sclarea L.) essential oil were presented. Antioxidant properties of the oil were evaluated by four different methods – DPPH, ABTS, FRAP, and CUPRAC. The oxidative stability of clary sage essential oil was provided at two temperatures 6 and 25°C. Using the Arrhenius equation the rate constant of the oxidative process was determined. Activating parameters as activation energy (Ea), enthalpy of activation (ΔH ++ ), the entropy of activation (ΔS ++ ), and Gibbs free energy of activation (ΔG ++ ) were calculated.