Over the past years, there has been an increase in concern regarding colloidal particle transport in soil. To date, there exists limited research on the fate and transport of these particles in the environment. In this study, a series of laboratory miscible displacement experiments were done using Fe/Ni particles. There is not enough data available in the literature about the transport mechanism of Fe/Ni particles. Although Fe/Ni particles have high reactivity with chlorinated solvents and metal ions, their transport properties are poorly understood, and the other uniqueness of this study was that it was done in clay soil and soil contaminated with perchloroethylene (PCE). These particles undergo collisions with soil grains and are subject to adsorption, dispersion, and retardation. Fe/Ni particles transport was studied in detail, and it was found that all mechanisms involved in particles transport in soil, which is the major contribution to environmental remediation. The Fe/Ni particle concentrations that were used were similar to those used in field studies for in situ treatment of chlorinated compounds. Fe/Ni particles were produced using solution method and characterized using SEM and XRD. The SEM micrograph of the Fe/Ni particles showed that the particles gave the mean size of Fe/Ni nanoparticles as a bimodel distribution of 249 and 3410 nm and were spherical in shape. Retardation factor and dispersion coefficients of Fe/Ni colloids in various clay soils were determined. The miscible displacement breakthrough curves indicated chemical nonequilibrium transport. The chemical nonequilibrium, miscible displacement model (two-site kinetic model) was used to describe the column breakthrough curves. This model resulted in excellent descriptions of the data.