A study was carried out on the effect of temperature (in the 500-800 degrees C range) and space-time (between 0.10 and 0.45 g(catalyst), h(g(bio-oil) )(-1)) on Ni/La2O3-alpha Al2O3 catalyst deactivation by coke deposition in the steam reforming of bio-oil aqueous fraction. The experiments were conducted in a two-step system, provided with a thermal step at 200 degrees C for the pyrolytic lignin retention and an on-line step of catalytic reforming in fluidized bed reactor. Full bio-oil conversion and a hydrogen yield of around 95% (constant for 5 h) were achieved at 700 degrees C, S/C (steam/carbon) ratio of 12 and space-time of 0.45 g(catalyst) h(g(bio-oil))(-1). The results of catalyst deactivation were explained by mechanisms of coke formation and evolution, which are established based on kinetic results and coke analysis by temperature programmed combustion. At 700 degrees C the coke is gasified and Ni does not undergo sintering. The results of hydrogen yield were compared with those obtained in the literature using different reaction technologies. (C) 2013 Elsevier B.V. All rights reserved.