The role of carboxyl groups in the disintegration of brown coal briquettes was investigated by means of water sorption on model briquettes made from acid-washed, cation-exchanged, water vapour-conditioned and heat-treated coals, Cracks were observed on the surfaces of briquettes with initial rates of sorption (r(ini)) of greater than 0.06 g-H2O g-coal(-1) min(-1). Results from acid-washed and cation-exchanged coals revealed that the carboxylate cations act as hydration sites to promote the disintegration, whilst carboxyl groups act as hydrogen bonding sites to prevent it, The water vapour-conditioned sample (having 1.2 times the carboxyl group content of the original coal) showed good resistance to the disintegration, The effectiveness of carboxyl groups in preventing the disintegration was demonstrated by a negative correlation between r(ini) and the amount of carboxyl groups present, Heat treated coals showed a rapid decrease in r(ini) up to 200 degrees C in which region there is no significant change in the carboxyl group content, This was explained in terms of suppression of swelling.