Natural products are always in demand, especially in the food and water treatment industry, to reduce health hazards caused by the prolonged use of chemicals. Though crude seed extract of Moringa oleifera (MOCE) is used for decolouration, the protein responsible for such activity is not fully known. In this study, in silico analysis of Moringa oleifera coagulant protein (MOCP; a predominant oligomeric protein in MOCE) was undertaken to check its molecular interactions with water and soil pollutants, in order to identify the protein accountable for such activities. The molecular docking studies of MOCP with azo dyes like congo red, tartrazine) and a pesticide (dichlorodiphenyltrichloroethane) revealed a strong binding affinity (-5.66, -5.33 and -5.04, respectively, kJ mol(-1)) between the protein and the pollutants through hydrogen bonding and electrostatic interactions. Further, these results were verified in situ with MOCP, a recombinant form of MOCP (MOCRP) and MOCE against congo red (100 mg L-1) and revealed the dye removal efficiency of 63.8%, 65.7%, and 72.3%, respectively. While the jar test results of synthetic coloured water and industrial textile effluent containing congo red showed 51.6% and 58.3%. Hence, we believe that the MOCP is responsible for multiple activities of MOCE and suggest its prospective use for large-scale treatment of drinking water and industrial effluents. (c) 2014 Society of Chemical Industry