Biomass gasification couples the high power efficiency with the possibility of valuably using the by-products heat and biochar. The use of agricultural wastes instead of woody feedstock extends the seasonal availability of biomasses. The downdraft type is the most used reactor but has narrow ranges of feedstock specifications (above all on moisture and particle size distribution), so tests on a demonstrative scale are conducted to prove the versatility of the gasifier. Measurements on pressure drops, syngas flow rate and composition are studied to assess the feasibility of such operations with corn cobs. Material and energy balances, and performance indexes are compared for the four tests carried out under different biomass loads (66-85 kg/h). A good operability of the plant and interesting results are obtained (gas specific production of 2 m(3)/kg, gas heating value 5.6-5.8 MJ/m(3), cold gas efficiency in the range 66-68%, potential net power efficiency 21.1-21.6%). (C) 2014 Elsevier Ltd. All rights reserved.