L-cystine and L-cysteine have been intercalated into magnesium-aluminum layered double hydroxide by the methods of coprecipitation and ion-exchange. The structure and composition of the intercalated materials have been characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. For L-cysteine intercalated composites, two kinds of well-crystallized materials with different basal spacing were obtained, as a result of the different charge on an ion and orientation of the gallery anions. The schematic models of the intercalation structures were proposed. In addition, the thermal decomposition of L-cystine and L-cysteine intercalated LDHs has been investigated by means of thermogravimetry and differential thermal analysis (TG-DTA).