ABSTRACT: In addition to petroleum, chlorinated ethylenes (CEs) containing tetrachloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE) and vinyl chloride (VC) are the most common organic ground-water contaminants. Environmental loads by these substances remain a huge problem in many old industrial areas, and they require rapid and effective remediation using environmentally friendly materials. Here, nano zero-valent iron (nZVI) and iron particles in higher valence states (ferrates) are promising remediation materials. This paper compares the efficiency of nZVI and ferrates combined with hydrogen peroxide during in-situ pilot remediation of area contaminated by CE in the surrounds of a Czech Republic metal industrial plant. The remediation process consisted of: (1) monitoring the area, (2) locating relevant hotspots, (3) selecting two most appropriate boreholes for application, (4) application and (5) post-application monitoring. nZVI suspension was applied in one of these boreholes and ferrates with hydrogen peroxide in the second. Obtained results were then compared. Reaction of ferrates with hydrogen peroxide was fast and very effective with a rapid onset of action during the first minutes, but the reaction lasted for only a short time. Reaction with using of nZVI had longer onset of action (during two weeks) and elimination efficiency was not so high, however the reaction was effective over a longer time frame (up to 8 months).