Abstract: A new family of immobilized phosphonic acid ligands attached to the surfaces of mesoporous sol-gel silicates has been synthesized. Three types of ligands have been prepared: a mono phosphonate, a methane bis-phosphonate and a linked diphosphonate all contain short alkyl linking groups to trialkoxy silane groups. The silane groups are readily grafted to the pore surfaces of the sol-gel supports. Hydrolysis of the phosphonic acid groups with TMSBr and water gives a new support surface wherein all surface silanols are capped with TMS groups as the phosphonic acid groups are made available. Both normal and "imprinted" sorbents have been prepared. The results of binding studies with Sr 2+ and UO2 2+ ions will be described