A series of 2,3-disubstituted 4-thiazolidinones 6 and 8a-p have been prepared by the cyclo condensation reaction of various substituted N-aryl hydrazones 5 and 7a– p with mercapto acetic acid. The intermediate N-aryl hydrazones 5 and 7a–p were synthesized by the condensation of 2-bromo-5-methoxy benzohydrazide 4 with 2 or various substituted aromatic aldehydes. The new Naphthalene-2-carboxaldehyde 2 has been synthesized by Vilsmeier-Haack reaction of naphthalen-1(2H)-one 1. The key starting compound 2-bromo-5-methoxy benzohydrazide 4 was prepared from methyl 2-bromo-5-methoxybenzoate 3 by the reaction with hydrazine hydrate in alcoholic medium. The formulae of the compounds were confirmed by elemental analyses and their structures were determined based on IR, 1 H-NMR, 13C-NMR, 13C-NMR-DEPT, and mass spectral data. The newly synthesized compounds were evaluated for their antioxidant, anti-inflammatory, and analgesic activities. The antibacterial activities of the newly synthesized compounds against E. coli ATCC 8739, S. aureus ATCC 6538, P. aeruginosa ATCC 1539, and Bacillus cereus, while the antifungal activities of the compounds against Candida albicans were tested. The acute cytotoxicity data of compounds 7h and 8a are tested and are found to be nontoxic up to 2,500 mg/kg.