Abstract The interaction of oblique monochromatic incident waves with a submerged horizontal porous plate has been investigated in the context of two-dimensional linear potential theory. The matched eigenfunction expansion method is applied to obtain the analytic solution. The present formulations, suggested by Molin and Nielsen (2004) and Liu and Li (2011) , are compared with the independent solutions using complex dispersion relations and they are proved to be identical. The former approach, however, may be more straightforwardly extended to the case of multi-layer horizontal porous plates. Also, the present predictions are compared with a series of experiments conducted in a two-dimensional wave tank at Jeju National University. By using the empirical relationship between plate porosity and porous parameter obtained by authors ( Cho and Kim, 2008 ), the measured reflection and transmission coefficients reasonably follow the trend of predicted values. The performance of the proposed submerged horizontal porous breakwaters can be significantly enhanced by selecting optimal design parameters, such as porosity, submergence depth, and plate width. The optimal cases are obtained through a systematic parametric study, which illustrates the usefulness of the presently developed analytic solutions.