In this study a novel coagulant, aluminium formate, was synthesised and its coagulation performance was evaluated. Aluminium formate can be synthesised from aluminium hydroxide and formic acid at atmospheric pressure and at a temperature of 60 degrees C. The speciation of the products obtained was studied using electrospray ionisation mass spectrometry. Aluminium formate was found to form mainly small cationic species in water. The coagulation performance was studied in removal of natural organic matter from surface water. Polyaluminium chloride and aluminium sulphate were used as reference coagulants. The results suggest that aluminium formate removes natural organic matter at least as well as the reference coagulants. Raw water characteristics were found to have an impact on the coagulation efficiency of the coagulants studied. Aluminium formate was found to be a potential water treatment chemical for applications where conventionally used coagulants cause problems. (C) 2011 Elsevier B.V. All rights reserved.