Six fly ashes from power stations fired with bituminous coal or lignites (SiO2/Al2O3 ratio 2.56-6.31, oxide modulus 5.89-8.70) were used as adsorbents for removing heavy metal ions from industrial wastewaters and sludges. A full removal of Cr3+ ions was achieved only in one case. The efficiency of the removal of Ni2+ and Cd2+ ions and immobilization of Zn2+ and PO43- ions was high (above 90%).