Grain and soybean dust explosion was investigated in order to determine the conditions that can cause an explosion to take place in a closed space such as in side a grain elevator, conveyor, miller and silo. The main parameters, which were investigated, were minimum ignition temperature, minimum explosible dust concentration, explosion pressure, dust particle size and moisture content. In all the materials and at all moisture contents, a concentration of about 1,000 g/m^3 was observed to give the maximum explosion pressure and maximum rate of pressure rise. The delayed time at this concentration was minimum. At any given dust particle size the ignition temperature was highest in rice husks followed by wheat, corn, milled rice and soybean in ascending order. However, in terms of maximum pressure and maximum rate of pressure rise, the order was from wheat, rice husks, soybean, corn to milled rice in descending order. It was observed that dust particle size played a major role on the explosibility of any dust material. Moisture content affected the ignition temperature and the maximum rate of pressure rise, but did not affect the maximum explosion pressure and delayed time of explosion.