Experiments were conducted by thermal gravimetric analysis (TGA) and cone calorimetry to measure the affect of three fire retardants (ammonium sulphate, boric acid and borax) on the mass-loss rate and combustion characteristics of sugar-cane bagasse. Compared with untreated bagasse, bagasse impregnated with aqueous solutions of 0.1-0.5 M fire retardants exhibited an increase in char mass production from 16% up to 41% when pyrolysed and up to a 41% reduction in total heat release (THR) during combustion. Char mass production was only a weak function of additive concentration over the range of concentrations (0.1-0.5 M) used. Combining the additives did not show any synergistic effects for char production or heat release rate (HRR). Treatment of bagasse by these chemicals could be useful to enhance biochar yields in pyrolysis processes or to reduce flammability risk in composites containing bagasse. (C) 2011 Elsevier Ltd. All rights reserved.