In this study, a methodology is proposed for obtaining information about the porous structure of materials by analysing data supplied by a hydric absorption test. A model of vertical cylindrical pores is used for studying the variation of absorbed mass versus time. The proposed methodology requires an estimation of the numerical interval in which the radius distribution must be calculated and a minimum amount of experimental data. The experimental tests are developed with a system, designed and built in our laboratory, that allows capture the amount of data necessary to use the calculus methodology proposed. This methodology is based on the derivative of normalized mass in relation to the square root of time of the capillary absorption tests. The simplicity and low cost, in many cases, of the capillary absorption tests compared to other experimental techniques such as mercury porosimetry or SEM, make it feasible to design a simple methodology to obtain valuable information about the structure of a porous material, pore size distribution, and tortuosity factor.