Ball milling technique was used to analyze the reductive dehalogenation of recalcitrant polyhalogenated pollutants. It was demonstrated that this ex situ degradation approach, designated as dehalogenation by mechanochemical reaction (DMCR), could be applied to both pure contaminants and contaminated materials, virtually regardless of their state. It was found that the DMCR method was virtually applicable to solids, liquids or mixed solid-liquid phases and materials due to intimate mixing and comminution process caused simultaneously by ball milling. It was also demonstrated that a ball mill simultaneously served as a mixing device and a reactor that mechanochemically activated and promoted the dehalogenation reaction.