With development of industry and population growth, awareness of hazards of water pollution as a universal threat has gradually increased and attracted considerable attention in the rest of the world. Absorption and photo-degradation are two of the most common methods for organic dye molecule removal in waste water. The main draw back with these common methods is that adsorbent does not separate easily. Thus in this work, the superparamagnetic Mn-MOF with core-shell nanostructures synthesized by in situ way was synthesized as a significant magnetic adsorbent for Malachite green removal. First, the magnetic core CoFe2O4 was synthesized by the co-precipitation method and then Mn-organic framework was sufficiently established on CoFe2O4 nanoparticles and made a fine core shell structure. The obtained nanostructure features were examined by TG-DT, SEM, TEM, BET, XRD, FTIR, and VSM techniques. In finally, the synthesized nanostructure was used for the adsorption of Malachite green with investigating three influence factors, pH of dyes, contact time, and agitation speed discussed with detail. The results show that CoFe2O4@Mn-MOF core-shell removes about 98% from water medium due to high adsorption capacity and porous structure which is a good candida to dye removal. (C) 2020 Elsevier B.V. All rights reserved.