Abstract: Effective in-situ injection technology for the remediation of dense nonaqueous phase liquids (DNAPLs) such as trichloroethylene (TCE) benefits from the use of decontamination agents that effectively migrate through the soil media, and react efficiently with both dissolved TCE and bulk TCE. A novel decontamination system contains highly uniform carbon microspheres preferably in the optimal size range for transport through the soil. The microspheres are preferably enveloped in a polyelectrolyte (such as carboxymethyl cellulose, CMC) to which preferably a bimetallic nanoparticle system of zerovalent iron and Pd is attached. The carbon serves as a strong adsorbent to TCE, while the bimetallic nanoparticles system provides the reactivity. The polyelectrolyte serves to stabilize the carbon microspheres in aqueous solution. The overall system resembles a colloidal micelle with a hydrophilic shell (the polyelectrolyte coating) and a hard hydrophobic core (carbon).