The effect of two pre-treatment techniques leaching and fractionation on the agglomeration problems observed during the gasification of the olive-oil residue material in a fluidized bed reactor was studied. The obtained results proved to be very positive in the case of leaching showing a substantial decrease of the agglomeration phenomena in the bed during the gasification tests compared with the results from the tests with the un-treated material. On the other hand, fractionation appeared to increase the ash reactivity leading to a dramatic increase of the agglomeration problems during the gasification process. (C) 2003 Elsevier Science Ltd. All rights reserved.