The governing equation describing wetted wall column is partial differential equation (PDE) which can be solved by similarity method. The selection of the combined variable to transform the PDE to an ordinary differential equation is very important subject in this method and mainly is selected based on experiences. But, in this work, a general combined variable was introduced for the PDEs transformation leading to a generalized analytical solution. The obtained analytical solutions were compared to literature and examined using some reported experimental data. According to the results, the deviations of calculated and collected experimental values were small which demonstrates accuracy and reliability of the presented method besides its highly computationally consistency and easy-to-use features. (C) 2017 Elsevier Ltd. All rights reserved.