The reaction of aryl halides with phenoxides and alkoxides were investigated under phase transfer catalytic conditions. 2,4-Dinitro- and 4-nitrohalobenzenes reacted readily with phenoxides in NaOH(aq)-benzene in the presence of Bu4N+Br, affording the products quantitatively. Although the aryl halides did not react with alkoxides under the same condition, the reactions were completed within 2 hours at room temperature when conducted under solid-liquid phase transfenr catalytic condition. The reactivity of aryl halides was in the order, Ar = 2,4-dinitrophenyl > 4-nitrophenyl, and X = F > Cl, consistent with the SNAr mechanism. The reactivity of oxyanions increased with the change of reaction condition from liquid-liquid to solid-liquid phase transfer catalysis. The results were explained with the concentration and the degree of hydration of the anion in benzene.