© 2020 European Association for Structural Dynamics. All rights reserved.Structural pounding is prevalent in general during earthquake shaking for adjacent structures in earthquake prone cities. In this study, the prevention of pounding effect is targeted by the optimal placement of viscous damping elements within the adjacent buildings. One of the important reasons of the pounding phenomenon is the out of phase vibrations of adjacent structures. A couple of adjacent structures which have different heights are modeled as shear buildings to set the proposed method. The relative displacement, defined as the extraction of horizontal displacements of adjacent structures at the top level of the shorter building, are chosen as the objective function to be minimized. In addition, reduction of relative displacement of the buildings and the effects of various vibration characteristics of each building is investigated based on transfer functions. Equations of motion of a structure, which are uncoupled when each structure is considered alone, become coupled when damping elements are placed in between the adjacent structures. The first mode response of the structures is considered while the transfer function response is derived. Optimal designs are determined for different total damping levels and different vibration characteristics of adjacent structures. The results of numerical analyses reveal that optimal designs effectively decrease the relative displacements between adjacent structures. Optimal designs are compared with the uniform design and without damper cases. The numerical analyses show that the proposed optimal damper design method in this study is vigorously effective for the prevention of pounding of adjacent buildings.