This chapter deals with the preparative methods, structural aspects and chemical-physical characteristics of hydrotalcite-like compounds (HTlc), an emerging class of layered solids with anion exchange and intercalation properties. Biocompatible HTlc can be modified with molecular anions having pharmaceutical, antimicrobial or antioxidant activity to obtain materials that can release the active anions in different environments with a de-intercalation process. Moreover, the organic-inorganic hybrids can exfoliate when dispersed in polymeric matrices and act as active fillers of biocompatible and biodegradable polymers. The fillers could enhance the mechanical and barrier properties of the polymer and confer on it biological activity for application in food packaging, particularly in active packaging technologies and in biomedical devices. © Woodhead Publishing Limited, 2011.