The purpose of the study described in this paper was to compare the removal of the heavy metals zinc, nickel, and copper from synthetic wastewater by using nanoparticles of CuFe ₂ O ₄ and NiFe ₂ O ₄ . The nanoparticles of nickel and copper ferrite (CuFe ₂ O ₄ and NiFe ₂ O ₄ ) were produced by the PEG assisted hydrothermal method. The structural and morphological characterizations were determined using XRD, FT-IR, and SEM. These nanoparticles were dispersed into synthetic wastewater contaminated with zinc, nickel, and copper. Once they had bound to the heavy metals, they were removed from the water solution using a strong magnet. The metal concentrations of the filtered samples were determined by using atomic absorption spectrophotometry (AAS). Then the heavy metal removal efficiencies and adsorption capacities of the nanoparticles (CuFe ₂ O ₄ and NiFe ₂ O ₄ ) were calculated. The removal efficiencies of Cu(II), Ni(II) and Zn(II) by using CuFe ₂ O ₄ nanoparticles was calculated as 83.50%, 98.85%, and 99.80%, respectively. The removal efficiencies of Cu(II), Ni(II), and Zn(II) by using NiFe ₂ O ₄ nanoparticles were calculated as 92.55%, 36.56 %, and 99.91%, respectively. The measurements were repeated several times with the same sample and almost the same results were obtained each time.