A fixed-sulfur, solid fuel product is obtained by an improved coking process wherein petroleum fractions are coked in the presence of added alkaline earth metal oxides. The fixed-sulfur, solid fuel product comprises coke and from about 3 to 30 weight percent, preferably from about 5 to 15 weight percent, "ash" (calculated as calcium oxide) derived from the alkaline earth additive. The quantity alkaline earth metal oxide or precursor thereof added to the coking zone is dependent on the sulfur content of the product coke and on the desired ash content of the solid fuel product. The coking zone may comprise delayed, fluid bed, or moving bed cokers.