Modeling the electric double layer of a porous body in contact with an electrolyte. In this work, the successful development of a model of the electric double layer on planar surfaces is achieved using the Gouy-Chapman-Stern double layer theory in Ansys Fluent. Additional considerations are made for modeling the electric double layer within a porous body. The model is created with the intention of future use with other models of an mMCDIcell from Technische Universität Dresden. In Ansys, several 2D-geometries based on the mMCDI cell are created, and different computational meshes are compared for application in the model. The modeling is performed without incorporating flow in the channel of the MCDI cell. The model equations are integrated using User-Defined Functions in Ansys Fluent. As a basis for the formation of the electric double layer, additional modeling of the electric field is conducted. The double layer model assumes the use of a 1:1-salt solution. The evaluation of the model results is based on the spatially dependent electric potential within the double layer and the ion concentration profiles for adsorbing co- and counterions. Keywords: digital modeling – electrical double layer – MCDI – Ansys Fluent Gouy-Chapman-Stern – saltwater treatment