Biomass gasification in fluidised bed with pure steam has already generated a 60 vol.%, dry basis, H2 rich gas that was increased to 70–80 vol.% H2 by using a CO2 sorbent in the gasifier bed. A tar content as low as 0.25 g/Nm³ has also been reported when an active catalyst is used in the gasifier bed. Biomass gasification in fluidised bed with pure steam, therefore, has some potential interest for the production of a very rich in H2 clean gas. This work shows in detail 12 operational variables that have already demonstrated a clear influence on the product distribution from the gasifier. Among all the products originating from the gasifier, this study concentrates on the hydrogen and tar contents in the raw gasification gas.