Abstract A 125 kg h −1 biomass gasifier of modular design was developed at the Sardar Patel Renewable Energy Research Institute (SPRERI) and tested on the thermal mode to test the concept. Based on these studies, a scaled-up 375 kg h −1 modular throat type, down-draft gasifier system was designed, developed and tested. The performance of the two systems is discussed in this paper. The smaller gasifier when tested at a wood consumption rate of 55 kg h −1 gave a gas calorific value of 4.24 MJ N m −3 and cold gas gasification efficiency of 63%. The larger gasifier system was operated for about 50 h using agro-residues briquettes at gas flow rates of 213 and 278 N m 3 h −1 . The cold gas efficiency was in the range of 70–73%. The gasifier was also operated at a gas flow rate of 460 N m 3 h −1 using wood as feedstock at a cold gas efficiency of 71%. The gasifier system was also tested continuously for 10 h without any problem and it produced good quality of gas consistently.