The paper reports results of a study on the use of active carbon from ammoxidated brown coal as electrode material for supercapacitors. The raw coal was subjected to demineralisation and ammoxidation by a mixture of ammonia and air, then it was carbonised and activated by steam or carbon dioxide. The electrochemical properties of carbons were determined by galvanostatic and potentiodynamic methods for water electrolytes. The best capacitance parameters of ca. 220 F/g in acidic and ca. 140 F/g in alkaline conditions were obtained for active carbon containing from 2 to 3 wt.% of nitrogen. (C) 2002 Elsevier Science B.V. All rights reserved.