A highly stable CoFe2O4 magnetic nanoparticles (MNPs) has been successfully prepared using a combined sonochemical and co-precipitation technique in aqueous medium without any surfactant or organic capping agent. The prepared (MNPs) were characterized with XRD, SEM, EDX, TEM, FT-IR and VSM. These nanoparticles form stable dispersions in aqueous or alcoholic medium. MNPs has been an efficient and environmentally benign nanocatalyst for the one-pot multicomponent synthesis of tetrahydrobenzo[h][1,3] thiazolo[4,5-b]quinolin-9-one 4a-p. The synthesized compounds easy work-up and purification of products by non-chromatographic methods. Highly yield of the corresponding products were obtained within a very short time in presence of just 6 mol% of the catalyst. (C) 2015 Elsevier B.V. All rights reserved.