The degradation by gamma radiation of four phenolic compounds (gallic acid, protocatechuic acid, vanillic acid and syringic acid) present in cork wastewaters was studied in several treatment conditions. The irradiations were performed under different pH (natural, 3, 7 and 10) and atmospheres (aerated, N2O and O-2) for isolated and aqueous mixture solutions of standard phenolic acids. The degradation of the compounds was higher in isolated than in the mixture solutions indicating a protective effect in the quaternary mixture solution. The saturation with N2O promoted the highest degradation rates for all phenolic acids in the mixture. However, at natural pH and in air it was achieved degradation efficiencies > 50% for gallic, vanillic and syringic acids in isolated and mixture solutions for a treatment dose of 20 kGy. It was verified that some of the compounds are a degradation product of the others, for example gallic acid was found to be a radiolytic product of syringic, vanillic and protocatechuic acids. Two different compounds were identified as radiolytic products of the studied phenolic acids, and their fragmentation pathways were proposed. The results highlighted that ionizing radiation could be used as clean technology for pollutants degradation using doses of 20 kGy.