A new series of 2,4-hexadienoic acid derivatives (S(1)-S(42)) has been synthesized and evaluated as antimicrobial agents against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans, and Aspergillus niger. Quantitative structure-activity relationship (QSAR) investigation using Hansch analysis was applied to find out correlation between antimicrobial activities with physicochemical properties of the synthesized compounds. Various physicochemical descriptors and experimentally determined minimum inhibitory concentration values for different microorganisms were used as independent and dependent variables, respectively. The QSAR revealed that topological parameters especially molecular connectivity indices (chi(2), (0)chi(v), (2)chi(v)) were found to have overall significant correlation with antimicrobial activity of 2,4-hexadienoic acid derivatives. The statistical results of training set, cross-validated r(2) and conventional r values gave reliability to the prediction of molecules with activity using QSAR models.