Mechanochemical (MC) treatment for degrading recalcitrant harmful PAH compounds (namely, anthracene and benzo[a]pyrene) adsorbed on marine sediments was investigated in laboratory. Optimal operating conditions (i.e ., mill rotation speed, milling time, milling-to-milled mass ratio), together with explanation of their physical effects on sediment particle size and specific surface area were assessed, leading to fast (30-60 min) and very effective (>98 %) degradation of both contaminants under the experimental conditions investigated. Attempts carried out through HPLC analysis and DTA checks before and after MC treatment permitted to envisage likely pathways for chemical reactions occurring during the process, yielding amorphous carbon as final product. Further research is planned to exclude the formation of noxious gaseous by-products.