The effect of CO2 capture in hydrogen production by steam reforming of the bio-oil aqueous fraction was studied. The reforming and cracking activity of the adsorbent (dolomite) and the relationship between these reactions and those corresponding to the catalyst (reforming and water gas shift (WGS)) were considered. The experiments were conducted in a two-step system with the first step at 300 degrees C for pyrolytic lignin retention. The remaining volatiles were reformed in a subsequent fluidized bed reactor on a Ni/La2O3-alpha-Al2O3 catalyst. A suitable balance was stricken between the reforming and WGS reactions, on the one side, and the cracking and coke formation reactions, on the other side, at 600 degrees C for catalyst/dolomite mass ratios >= 0.17. At this temperature and space-time of 0.45 g(catalyst) h (g(bio-oil))(-1), bio-oil was fully converted and the H-2 yield was around 99% throughout the CO2 capture step. Catalyst deactivation was very low because the cracking hydrocarbon products (coke precursors) were reformed.