Background: Cancer caused nearly 8.8 million deaths in 2015. Limited efficacy, selectivity, drug resistance and toxicity are major complications associated with chemotherapy, potentiating the discovery of anticancer agents. Methods: A new series of N-(7-hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide/benzamide analogues (5a-j) was prepared from the precursor, 7-hydroxy-4-methyl-2H-chromen-2-one (3), as anticancer agent. The structural assignment of quinolone analogues (5a-j) was based on spectroscopic data analyses. The cytotoxicity was tested on breast cancer cell lines (MCF7 and MDA-MB- 231) by sulforhodamine B (SRB) assay and three dose-related parameters GI50, TGI, and LC50 were calculated. Results: 2-(2-chlorophenoxy)-N-(7-hydroxy-4-methyl-2-oxoquinolin-1(2H)-yl)acetamide (5a) showed the most potent cytotoxicity against the MCF7 and MDA-MB-231 cancer cell lines with GI50 of 18.7 and 48.1 µM respectively. The glide scores of the compounds, 5a-d were found to be related to the cytotoxicity profile and the emodel scores for ligands, 5a-j were found to be related to significant cytotoxicity. Conclusion: Compound 5a exhibited the most potent cytotoxicity and this report may provide some predictions to design more potent novel quinolines as cytotoxic agents.