Abstract: The present invention relates to a method for reducing agglomeration, sintering and deposit formation resulting from the gasification or combustion of a solid carbonaceous fuel material comprising a combustible portion and a non combustible inorganic portion, which non combustible inorganic portion comprises 4 to 50 parts by weight of Kw+Naw, and 0 to 40 parts by weight of Siw, wherein Kw is potassium, Naw is sodium, and Siw is silicon, all calculated in parts by weight of the elements per 100 parts by weight of the inorganic portion, and optionally also chloride, phosphorus, calcium and sulphur which method is characterised in adding to the fuel before or during the gasification or combustion, Padded parts by weight of phosphorus compound calculated as P wherein the amount Padded is calculated in accordance with the formula I Padded=q1×(31/39 Kw+31/23 Naw−Pw−31/35,4 Clw)  (I) wherein q1=0.