An aqueous macroemulsion to be used in place of petroleum residuum-based fuel oils such as No. 4, No. 5, and No. 6 fuel oils, as well as the vacuum residuum from the fraction distillation of petroleum, is formed by emulsifying the fuel oil with water or an aqueous liquid, the fuel oil forming the dispersed phase and the aqueous liquid forming the continuous phase. An emulsion stabilizer, and optionally various other additives, notably a lower allyl alcohol, are included to stabilize the properties of the emulsion. The emulsion is prepared by heating the fuel oil, particularly No. 6 fuel oil, and the water to a temperature above about 60° C., and combining the two heated liquids in an appropriate ratio and shearing the mixture to form the macroemulsion. The macroemulsion offers numerous advantages over the fuel oil itself including the fact that it can be pumped at ambient temperature rather than requiring heating, and that it is a clean-burning fuel with significantly lower emission of NOx and other pollutants and contaminants.