The effect of NaOH concentration of the substitution reaction of hexachlorocyclotriphosphazene, N3P3Cl6, with phenol was performed to synthesize the partially substituted (phenoxy) chlorocyclotriphosphazenes, N3P3Cl6-i(OC6H5)(i), i = 1-6 by phase-transfer catalysis (PTC) in an organic phase/alkaline solution. The reaction system was controlled by both chemical kinetics and mass-transfer effects. The relationship between the functions of NaOH in a PTC reaction such as (i) salting out the intermediate product of catalyst QY to the organic phase and (ii) reducing the solvation between the catalyst and water to enhance the reactivity of active catalyst in the organic phase, and the mass transfer capability of the catalyst between both phases was clarified. In addition, the corresponding energies, enthalpies and entropies of activation of the series substitution were also estimated.