Deformable mirrors are vital components of any adaptive optical system. Considering such a crucial role in compensation of incident wavefront distortions, the main requirements are imposed on these elements that determine performance of the entire system. To correct for phase distortions in high-power laser complexes a stacked-actuator deformable mirror with water cooling was developed. The main characteristics of the mirror, such as the initial surface profile (flatness), response functions of the actuators, maximal stroke, and amplitude-frequency characteristics are presented in this paper. Experimental investigations of the proposed cooling method of the mirror surface through actuators were performed.