Steam and air-steam biomass gasification tests, were performed in a fluidized bed gasifier in absence and in presence of catalytic and non-catalytic ceramic filters, delivered by Pall Filter-systems GmbH Werk Schumacher. Auto thermal conditions were achieved for the air to fuel ratio divided by the air to fuel ratio for the stoichiometric combustion ER equal 19.6 %. The catalytic filter shows is effectiveness to reduce tar, CH4 and NH3 in the producer gas, when only steam is utilized. By performing biomass gasification tests in presence of the mixture air-steam, the amount of organic compounds heavier than naphthalene increases considerably and account for more than 20 % of the total tar. These high molecular weight organic compounds are more difficult to be transformed in light gases. For these tests, in presence of non-catalytic and catalytic filters the reduction of tar was 22 % and 54 %.