The interplay between oxidative stress and inflammation is implicated in many chronic diseases including Alzheimer`s disease, cardiovascular diseases, diabetes and cancer. Thirteen β-hydroxy-β-arylalkanoic acids were previously synthesized and evaluated for their anti-inflammatory activity. The aim of this study was to asses ex vivo antioxidant activity of synthesized acids, as well as ibuprofen and to identify the compounds with the most promising results for further investigation on their capacity to counteract in vivo oxidative stress triggered by inflammation. The antioxidant potential of tested compounds was evaluated by determining the concentrations of total antioxidative status, total oxidative status, prooxidant antioxidant balance and the total sulfhydryl groups. Z score statistics were used to calculate the summary scores for antioxidative activity, prooxidative activity and oxy score. The tested compounds and ibuprofen demonstrated mild prooxidative activity ex vivo. Seven acids with substituents on one benzene ring exhibited better results than ibuprofen and were selected for in vivo testing. In vivo results demonstrated better antioxidant protection compared to ex vivo results. Compound g which contains nitro group on the benzene ring demonstrated the lowest oxy score, and four compounds exhibited better results than ibuprofen.