Modification of the surface of porous silicates, such as clays and zeolites, with functionalized organic monolayers has recently attracted widespread interest, since these organic-inorganic hybrid materials have great potential for environmental and industrial applications. Covalent attachment of the organic functionalities onto clay layers usually occurs through chemical grafting involving the surface hydroxyl (OH) groups as anchoring sites. In our approach, organoclays have been synthesized in a direct one-step co-condensation process between magnesium chloride (MgCl2) and organoalkoxysilanes ((C2H5O)3Si-X) bearing various functional groups (X = (CH2)3NH2, (CH2)3SH…), so that the formation of the functionalized layers does not depend upon the surface OH groups. The materials obtained can be processed into powder or thin films. Structural characterization indicates a disorganized layered clay-like structure, similar to that of natural talc, and high contents of fairly mobile organic moieties incorporated intact into the framework. We also investigated the possibility of modifying the hydrophobic character of these organoclays, by incorporating alkoxysilanes (e.g. (C2H5O)4Si) in the synthesis. We investigated the reactivity of the anchored organic functions by reacting an amino-functionalized solid with several aldehydes and by using a thiol-functionalized derivative as scavenger for aqueous heavy metal ions (Hg2+, Pb2+ and Cd2+). The high reactivity and sorption capacity of these materials was interpreted in terms of high concentration of reactive sites readily accessible through the expansion of ability of the framework.