Alumina has been used as a selective solid adsorbent for a scaleup test of a jet fuel and diesel fuel desulfurization technique. The oxidative process with ultrasound assistance has been improved for practical purposes by using solid adsorption instead of solvent extraction. Therefore, the advantages of both oxidative and adsorptive desulfurization have been put together for a modified continuous system to provide a source for portable fuel cells. Refractory sulfur compounds of benzothiophene and dibenzothiophene derivatives have been removed at 99% efficiency. The sulfur concentration in JP-8 jet fuel can be reduced from the original 850 ppm to 1 ppm at an oxidation time of 10 min at ambient temperature and atmospheric pressure. Gas chromatograms from gas chromatography-sulfur chemiluminescence detection and gas chromatography-pulsed flame photometric detection evaluate the efficiency and selectivity of the ultrasound-assisted oxidative desulfurization (UAOD) process on different fuels after adsorption. gas chromatography-flame ionization detection, gas chromatography-mass spectrometry, and gas chromatography-simulated distillation were used to identify the concentration changes of sulfur compounds and hydrocarbons in fuels during the process. High sulfur adsorption capacities were obtained due to high conversion rates of the UAOD process. For marine gas oil, 12.8 mg of sulfur was removed per gram of alumina, which indicates the optimized process without the use of composite adsorbents. Acidic alumina shows promising results as an adsorbent in the UAOD process. Experiments prove that solid adsorbents are suitable for a scaleup to achieve ultralow sulfur fuel in the UAOD process.