Kaolin–OSO3H efficiently catalyzes the condensation of 2-aminobenzenethiol or benzene-1,2-diamine and 2-bromo-1-aryl-ethanones to yield quinoxaline and benzothiazine derivatives in good yields. The sulfuric acid modified nano kaolin was synthesized with a simple and low-cost method. The present method also has the advantages of good to excellent yields, short reaction times, operational simplicity, and a natural and green catalyst.