Montmorillonite (Mnt), belonging to the smectite group and representing a 2:1-type clay mineral with good cation-exchange and swelling capacities, is a common clay component of soils. It was observed that some Mnt preparations exhibit peroxidase-like (P-L) activity using N,N-diethyl-p-phenylenediamine sulfate salt as a substrate. Both native (non-swelling) and swelling Mnt exhibited similar P-L activity. Modification of Mnt with copper and iron influenced both P-L activity and phenol polymerization. Both free and textile-bound Cu-Mnt (Sigma-Aldrich) enabled phenol removal. Soil Mnt P-L activity is probably involved in lignin breakdown and decontamination of soils polluted with phenol-containing molecules.