We present results concerning the characterization of selected silica-based materials from a molecular modeling approach, together with some physical and mathematical tests to check the reliability of the obtained results. The experimental adsorption data is used in combination with Monte Carlo simulations and a regularization procedure in order to propose a reliable Pore Size Distribution (PSD). Individual adsorption isotherms are obtained by Monte Carlo simulations performed in the Grand Canonical ensemble. The methodology is applied to M41S materials, chosen due to their well defined pore geometry and pore size distribution, obtainable from alternative procedures. Our results are in excellent agreement with previous published results, demonstrating the reliability of this methodology for the characterization of other materials, with less well-defined structural properties.