The effect of liquid height on chemical reactions induced by sonication was investigated under a low frequency of 44.3 kHz using a large-scale parallelepiped sonochemical reactor. The experiments were conducted with the liquid height of 87 to 592 mm, which were equivalent to the sample volumes of about 18-80 dm(3). The effect of the liquid height was evaluated by calorimetry and potassium iodide (KI) dosimetry. The results demonstrated that there existed an optimum liquid height to enhance sonochemical reactions in the large-scale sonochemical reactor. As a result, it was found that the sonochemical efficiency of the large-scale sonochemical reactor was much higher than that of the laboratory-scale sonochemical reactor below 0.2 dm(3) in the sample volume reported previously.