The increasing oil prices during the last years have made it profitable to use cereal grains as a fuel. When compared with wood, cereals contain higher amounts of Cl, S and ash. The Cl and S content makes the gases from cereal combustion more corrosive than gases from wood combustion. The goal of this master thesis was to find out the variation of Cl, S and ash content for oat grain grown under different conditions. Oats was chosen because in Sweden it's considered as the cereal with the best fuel qualities.