Well-crystallized kaolinite was initially reacted at 60 degrees C with a water-dimethyl sulfoxide mixture. After washing and characterization, the resulting material (Al2Si2O5(OH)(4)(DMSO)(0,4)) was reacted with 1-methyl-2-pyrrolidone (NMP) at room temperature. The product was a light yellow powder with a stoichiometry that attests to the quantitative substitution of the DMSO by the NMP molecules. (Al2Si2O5(OH)(4)(NMP)(0,39+/-0.02)) was characterized by X-ray diffractometry, thermal analysis (simultaneous TG and DSC), and FTIR. The fact that the NMP molecules are located in the interlamellar space of the kaolinite permits a notable enhancement of the thermal stability of the complex. While the DMSO-derived system decomposes at 175 degrees C under air, the NMP complex remains stable up to 431 degrees C.