To demonstrate the impact of clay mineralogical composition and proportion on the textural and structural properties modification, specific surface area, porosity, pore size distribution, pore volume, pore diameter and morphology after acidic activation. Its effect depends on the proportion of the 2:1 phyllosilicate. Three clayey series outcropping aged from Upper Cretaceous to Paleogene from the Zaghouan area in Tunisia were studied. The X-ray diffractions of clay fractions shows that they are mostly made up of smectite type. The rates of octahedral and tetrahedral substitutions were determined by the cation exchange capacity (CEC) before and after Li-saturation coupled with chemical analysis. The destruction rate of clays is determined after 6 hours of acid treatment and is equal to 76 and 79% respectively for Za1 and Za3 samples. The Scanning Electron Microscope was used to detect the morphological change of the activated samples, it show the dissolution and the corrosions of clay after acid treatment, and they are much more pronounced during the progression of acid treatment. The specific surface area increases with the treatment time to reach very high values at 3 hours. The pores become more developed between particles and they are more pronounced as acid dissolution progressed.