Strontium uptake by an aluminum pillared montmorillonite has been studied in aqueous solutions of pH values ranging from 3 to 8. Desorption of Sr 2 + has been observed when the concentration of H 3 O + in the solution raises. In order to limit this effect, the material has been modified by inserting organic molecules in the interlayer. Results with glycerol and oxalic acid as modifying agents demonstrate that it is feasible to shield the metal cations against hydronium attack and thus reduce strontium desorption in acidic environments. These results are of a particular interest from a view point of the potential application of PILCs as antidotes against strontium radiocontamination of ruminants.