This study is focused on the improvement on the porous material characterisation, measuring the transition stage between the saturated and dry phases, which has been defined in literature as the critical moisture content (c). This study develops a procedure based on Quantitative IR Thermography (QIRT) determining the effective c, as a physical property for the porous material. The c for San Marco bricks were examined in laboratory by QIRT and the standard gravimetric method (SGM). It was seen that QIRT can be used to determine the c and was also found to be more practical and sensitive than the SGM. The results obtained in the laboratory were promising to give the hints of methods for quantitative moisture content measurements and in-situ QIRT investigations.