Four macrophytes commonly used to clean up Cu contaminated effluents, i.e. Arundo donax L., Cyperus eragrostis Lam., Iris pseudacorus L. and Phalaris arundinacea L., were assessed to produce Cu-rich plant biomass intended for ecofriendly catalyst preparation. 7-month-old plants were exposed to a Cu gradient (0.08, 2, 10, 20 and 40 mu M Cu) in batch conditions during 2 months. Copper exposure affected the root DW yield of C. eragrostis from 2 mu M Cu, whereas I. pseudacorus and A. donax developed well. Maximum Cu concentration in the biomass of C. eragrostis and P. arundinacea (i.e. 255 and 838 mg Cu kg(-1) DW respectively) did not reach the 1000 mg Cu kg(-1) DW threshold value needed to produce Cu-ecocatalysts. Copper concentrations in the roots of I. pseudacorus and A. donax exceeded this threshold value at 40 mu M and over 10 mu M Cu, i.e. 1099 and 1809 mg Cu kg(-1) DW, respectively, making them relevant candidates for producing Cu-ecocatalysts.