Spherical iron-carbon nanocomposites were synthesized through a facile aerosol-based process and a subsequent carbothermal reduction. The distribution and immobilization of iron particles throughout the carbon microspheres prevents nanoiron aggregation, allowing the maintenance of particle reactivity. The carbon microspheres allow adsorption of TCE, thus removing dissolved TCE rapidly and facilitating reaction by increasing the local concentration of TCE in the vicinity of iron particles. The strongly adsorptive property of the composites may prevent release of toxic chlorinated intermediate products. The nanoscale composite particle size is in the optimal range for effective transport through groundwater saturated sediments. It is also shown that carbothermal treatment of the composite material leads to highly porous carbon materials containing zerovalent iron species, a necessary reactive component in the reaction pathway. The mesoporous structure generated allows access to internal reactive sites.