The influence of oxidation on the production of high-porosity carbons from phenol-formaldehyde resins with KOH activation were examined under various preparation conditions. The activation process principally consisted of KOH impregnation followed by carbonization. Experimental results showed that prior to carbonization treating the resins with oxygen at 120 degrees C, either before or after KOH impregnation, enabled the enhancement of the yield of the carbon products. The porosity development was found to be hindered by conducting oxidation prior to the impregnation. For oxidation performed after the impregnation, at a low KOH/resin ratio the porosity was found to decrease upon oxidation, whereas the oxidation enhanced porosity development for activation performed at higher ratios. Varying the carbonization temperature and time did not show obvious influence on the effects of the oxidation.