This paper presents an environmentally friendly and efficient method for degrading methylene blue, a common pollutant in wastewater, using a catalyst-free dual-frequency ultrasound treatment. The study investigates the use of two different frequencies (20 kHz and 80 kHz) to enhance the quality of cavitation bubbles, which are crucial for the degradation process. The results show that dual-frequency ultrasound consistently outperforms single-frequency modes under identical acoustic power density conditions. The larger the difference between the dual frequencies, the more effective the degradation. After 20 minutes of sonication at an acoustic power density of 209.63 ± 6.94 W/L, a degradation efficiency of 91% was achieved. The study also examines the impact of frequency differences on degradation efficiency, finding that the combination of 20 kHz and 80 kHz frequencies yields the highest efficiency. The degradation pathway involves the formation of hydroxyl radicals and hydrogen peroxide, leading to the mineralization of methylene blue into simpler inorganic molecules. The total organic carbon (TOC) removal efficiency was 87.42% after 20 minutes of treatment. The kinetics of the degradation process follow first-order kinetics, with rate constants of 0.055 min\(^{-1}\) and 0.043 min\(^{-1}\) for the 20/80 kHz and 20/37 kHz dual-frequency treatments, respectively. This method provides a promising, additive/catalyst-free approach for methylene blue degradation.This paper presents an environmentally friendly and efficient method for degrading methylene blue, a common pollutant in wastewater, using a catalyst-free dual-frequency ultrasound treatment. The study investigates the use of two different frequencies (20 kHz and 80 kHz) to enhance the quality of cavitation bubbles, which are crucial for the degradation process. The results show that dual-frequency ultrasound consistently outperforms single-frequency modes under identical acoustic power density conditions. The larger the difference between the dual frequencies, the more effective the degradation. After 20 minutes of sonication at an acoustic power density of 209.63 ± 6.94 W/L, a degradation efficiency of 91% was achieved. The study also examines the impact of frequency differences on degradation efficiency, finding that the combination of 20 kHz and 80 kHz frequencies yields the highest efficiency. The degradation pathway involves the formation of hydroxyl radicals and hydrogen peroxide, leading to the mineralization of methylene blue into simpler inorganic molecules. The total organic carbon (TOC) removal efficiency was 87.42% after 20 minutes of treatment. The kinetics of the degradation process follow first-order kinetics, with rate constants of 0.055 min\(^{-1}\) and 0.043 min\(^{-1}\) for the 20/80 kHz and 20/37 kHz dual-frequency treatments, respectively. This method provides a promising, additive/catalyst-free approach for methylene blue degradation.