This study describes tar conversion on olivine in fluidized-bed gasification conditions. A laboratory-scale reactor (Aligator) was used to characterize phenol conversion to higher tars, before adding a sand and olivine bed to investigate heterogeneous steam reforming and the cokefaction of these tars. H2 and H2O atmospheres were tested both separately and together to characterize tar conversion on olivine. Catalytic activity in steam reforming was shown to be much improved by the presence of H2. In the absence of H2O in the reactive atmosphere, olivine caused a high cokefaction of tars. With 10% H2O and 20% H2, olivine became highly active in steam reforming of tars. Carbon deposition on the catalysts was quantified by temperature-programmed oxidation (TPO), and optical photographs of olivine were taken after tar conversion.