<p>In this study, an efficient method of generating OH radicals by the interaction between underwater shock waves and elastic thin films was investigated. The generation and propagation of underwater shock waves, as well as the creation of microbubbles, were observed through experimental imaging techniques such as Schlieren and shadowgraph methods. A correlation was found between the creation of cavitation bubbles and the acoustic impedance values of the elastic films. Specifically, it was observed that a higher difference in acoustic impedance value between water and elastic films resulted in a greater number of microbubbles being generated. Notably, the number of bubbles was significantly increased when expansion waves generated by shock wave reflection interacted with the surface of high-impedance materials. Furthermore, in the investigation of OH radical generation by measuring the concentration of hydrogen peroxide, it was found that the highest production of OH radicals occurred when Ar gas was dissolved in degassed water. This suggests that Ar gas, due to its higher specific heat ratio compared to other gases, led to an increase in temperature within the bubble. Consequently, this acceleration of the thermal decomposition reaction of water molecules resulted in a greater amount of OH radicals being generated.</p>