The study of the chemical effects of ultrasound is a rapidly growing research area, and its use in heavy crude oil upgrading has been explored. In this work, hydrogenation of cyclohexene, biphenyl, and quinoline and hydrodesulfurization of benzothiophene in the presence of formic acid (a hydrogen precursor), a Pd/C catalyst, and ultrasound irradiation is investigated. It was found that the use of formic acid in the presence of ultrasonic irradiation was an effective system for promoting the hydrogenation of cyclohexene (98%) and biphenyl (21%), the desulfurization of benzothiophene (18%), and the hydrogenation of quinoline (19%) at very mild conditions (i.e., ambient temperature and pressure).