The characterization of pore structures is required for a broad range of applications, from modelling flow dynamics to understanding petroleum reservoir performance. This research was based on a theoretical framework proposed by Abou Najm and Atallah for improved characterization of pore structures using Newtonian and non-Newtonian fluids. Here, we report the first experimental evidence of the ability of non-Newtonian shear-thinning fluids to predict the pore structure of three synthetic porous media using only saturated infiltration experiments of water and guar gum solutions at different concentrations. The method predicted multiple distinct representative pore sizes, depending on the number of guar gum solutions used, optimized to mimic the functional behaviour of porous media in terms of flow and porosity. Statistical analysis revealed satisfactory agreement between the predicted and real pore structures in the three synthetic porous media. Highlights: Experimental evidence of the ability of non-Newtonian fluids to infer the pore structure of porous media Experiments enabled extraction of multi-flow regimes mimicking functional flow and porosity behaviour Experiments with different guar gum concentrations on three synthetic porous media regenerated known pore structures Promising results for an inexpensive and safe new method for pore structure characterization.