Coal samples from concentrate of Shahroud coal preparation plant with an ash content of 13.8% and a total sulfur content of 1.89%, without pretreatment and also with pretreatment by microwave irradiation, ultrasonic waves, and microwave followed by ultrasonic (microwave- ultrasonic), was leached with HF and then HNO₃ to produce ultraclean coal (UCC) in a batch reactor. Irradiation pretreatments, in the order of microwave-ultrasonic > ultrasonic > microwave had positive effects on acid leaching with HF, especially for coarse size fractions and early in the leaching process. After HF leaching, the HNO₃ complementary leaching was more effective on the microwave-ultrasonic pretreated sample, where, after processing, 95.5% ash content of the sample was removed. A comparison between sulfur content of samples before (1.89%) and after leaching (HF followed by HNO₃) shows that the sulfur content of nonpretreated sample decreased to 1.26%, whereas this reduction for microwave-ultrasonic pretreated sample was more noticeable by 0.8%. The results indicated that microwave-ultrasonic irradiation can be considered as the most effective pretreatment method in the chemical leaching of coal to produce UCC.