The influence of the technological parameters on the epoxidation of (Z,E,E)-1,5,9-cyclododecatriene (CDT) with 30% hydrogen peroxide to (E)-1,2-epoxy-(Z,E)-5,9-cyclododecadiene (ECDD) was studied under the conditions of phase transfer catalysis (PTC), in the presence of H3PW12O40/Aliquat 336 catalytic system. The parameters considered included stirring speed, the molar ratios of CDT:H2O2 and H2O2:H3PW12O40, temperature, and the nature and concentration of solvent. The variation ranges of these parameters ensuring a high CDT conversion and high selectivity of transformation to ECDD were established. The CDT conversion was 51.4-55.6% and the selectivity of transformation to ECDD was 79.8-95.1%.