Synthesis, antioxidant activity, and quantitative structure-activity relationship (QSAR) of 25 of chalcone derivatives is reported here. They were synthesized by Claisen-Schmidt reaction and were characterized by FTIR, NMR, and mass spectroscopy. Antioxidant activity is evaluated through four different methods namely, superoxide radical-scavenging, hydrogen peroxide scavenging, reducing power, and DPPH radical-scavenging assays. Generally, compounds with -SCH3 and -OCH3 in the para position of the A-ring and -OH in the B-ring were more active than others. In few cases some of the compounds were more active than ascorbic acid or butylated hydroxytoluene. QSAR was developed correlating the antioxidant activity with the structural features of the compounds and the predictive capability of the models was estimated using internal and external validation methods. All the predictions were within the 99% confidence level. Spatial, structural, and lipophilic properties of the compounds determine their antioxidant properties. © 2011 Springer Science+Business Media, LLC.