The effective implementation of biomass gasification has to overcome some difficulties such as the minimization of tars. On the other hand, with a proper design of experimental conditions, biomass gasification can be directed towards the production of hydrogen. The aim of the present study was to investigate the use of dolomite as catalyst to improve tar removal and hydrogen production by a two-stage steam gasification process, using olive cake as raw material. Fixing the olive cake gasification conditions on the first reactor (900 degrees C, steam flow rate of 190 mg min(-1), O(2) flow rate of 7.5 cm(3) min(-1)), the cracking of tars was prompted by: a) steam gasification (steam flow rate in the range 40-190 mg min(-1)) at 1000 degrees C, b) catalytic gasification, using dolomite (5% wt.). It was found that increasing steam flow rate up to 110 mg min(-1) involves an increase in hydrogen fraction due to the enhancement of water gas and water gas shift reactions. Also, the influence of dolomite was studied at 800 and 900 degrees C in a second reactor, finding better results at 800 degrees C, which gave an hydrogen fraction of 0.51. (C) 2011 Elsevier Ltd. All rights reserved.