A series of 3-(2-aminothiazol-4-yl)quinolin-2[1H]-ones 3 was prepared by neat reaction of quinolin-2[1H]-ones 1 with thioureas 2 in the presence of molecular iodine. The synthesized compounds were evaluated for their in vitro antimicrobial activities against Escherichia coli, Paedococcus sp., Lactobacillus, Yersinia enterocolitica, and Staphylococcus aureus. The green chemical approach for the synthesis of thiazoloquinolinone 3 was performed under neat conditions using molecular iodine as catalyst as well as reaction medium. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright © Taylor & Francis Group, LLC.