Iron and iron oxide nanoparticles (NPs) are finding wide applications for the remediation of various toxic chloro-organic compounds (such as trichloroethylene, TCE) via reductive and oxidative processes. In this study, Fe NPs (30-50 nm) were synthesized by reduction from ferric ions immobilized (by ion exchange) on a platform (two types of sulfonated silica particles) in order to prevent NP agglomeration. The Fe NPs were then oxidized and their effectiveness for the oxidative dechlorination of TCE via the heterogeneous decomposition of hydrogen peroxide to OH center dot on the surface of the iron oxide NPs was demonstrated. For the reductive approach, the use of ascorbic acid as a "green" reducing agent in conjunction with a secondary metal (Pd) inhibits NP oxidation and agglomeration through surface adsorbed species. The Fe/Pd NPs have been successfully applied For the dechlorination of TCE (k(SA), surface-area normalized reaction rate, = 8.1 x 10(-4) L/m(2) h).