Producer gas through gasification of biomass can be used as an alternate fuel in rural areas due to high potential of biomass resomces in India.Experiments were conducted to study the performance of a diesel engine (four stroke,single cylinder,5.25 kW) with respect to its thermal efficiency,specific fuel consumption and diesel substitution by use of diesel alone and producer gas-cum-diesel (dual fuel mode).Three types of biomass,i.e.wood chips,pigeon pea stalks and com cobs were used for generation of producer gas.A producer gas system consisting of a downdraft gasifier,a cooling curm cleaning unit,a filtering unit and a gas air mixing device was designed,fabricated and used to power a 5.25 kW diesel engine on dual fuel mode.Performance of the engine was reported by keeping biomass moisture contents as 8％,12％,16％,and 21％,engine speed as 1 600 r/rmin and with variable engine loads.The average value of thermal efficiency on dual fuel mode was found slightly lower than that of diesel mode.The specific diesel consumption was found to be 60％-64％ less in dual fuel mode than that in diesel mode for the same amount of energy output.The average diesel substitution of 74％ was observed with wood chips followed by corn cobs (78％) and pigeon pea stalks (82％).Based on the performance studied,the producer gas may be used as a substitute or as supplementary fuel for diesel conservation,particularly for stationary engines in agricultural operations in the farm.