This dissertation attempts to extend the novel concept of Oxidative Desulfurization, invented during the late 90s, to fuels heavier than light naphtha, which was the initial most promising application. As a result, herein it is presented a novel process for desulfurization of hydrocarbon fuels in general, including heavier fuels such as Diesel and Heavy Fuel Oil (HFO). In general, the process consists of two steps: first, the hydrocarbon is submitted to an oxidation reactor, most commonly consisting of an ultrasonic chamber, where sulfur compounds are oxidized to sulfones; then, the sulfone-rich hydrocarbon is submitted to a catalytic steam cracking process, Aquaprocessing (AQP), where the sulfones are decomposed, and the desulfurized oil is produced. Three industrial Heavy Fuel Oil feedstocks and three industrial Diesel feedstocks were processed in this study. The investigation of the oxidation part of the process was more comprehensibly carried out during the processing of HFOs. Parameters such as Oxidant/sulfur molar ratio, residence time, ultrasound irradiation energy and reaction temperature were studied. The AQP part of the process was studied more comprehensibly during the processing of the Diesel feedstocks, including the reaction temperature and the testing of different catalysts. Under the conditions tested in the integrated process, one HFO feedstock, RMG-380, was desulfurized to close to 0.5% wt. sulfur (60% desulfurization), while the two others were more refractory, and were not able to be desulfurized to less than 1.3% wt. sulfur. On the other hand, all the three Diesel feedstocks were desulfurized to less than 500 ppmw. This study demonstrates and highlights the potential of this novel approach for desulfurization of all types of fossil fuels.