A series of novel 4-Hydroxy-1-methyl-3-(3-substituted)-4,5-dihydroisoxazol-5-yl)quinolin-2(1H)-one derivatives were synthesized from chalcones (α, β-unsaturated compounds) well known compounds to exhibit antioxidant activities. All the synthesized compounds were characterized by spectral and analytical data and were evaluated for antioxidant activity by DPPH method using standard Ascorbic acid. All the compounds are known to exhibit antioxidant activity. Among them, compound (5f) exhibited the IC50 = 7.2 μM, standard (IC50 = 5.85 μM)