<p>In this study, the biosorption efficiency of Cu(II) ions from aqueous solutions by using EDTA complexed magnetic thistle (EMT) was investigated in batch system. The characterization of thistle, EMT, and Cu(II) loaded EMT was performed through Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray analyses (EDX) and zeta potential measurements. Experiments were applied as a function of pH, biosorbent dosage, contact time, and temperature. Optimum Cu(II) uptake capacity was determined at the biosorbent dosage of 8 g L⁻¹ at pH 4. The contact time of 20 min was sufficient to reach the equilibrium at all the temperatures. A slight increase in biosorption capacity was observed with the increasing temperature, pointing to the endothermic nature of the process. The biosorption data adapted well to the pseudo-second-order kinetic and Langmuir isotherm models, with fairly high correlation coefficient values. The maximum monolayer biosorption capacity was found to be 55.30 mg g⁻¹ at 45 ⁰C. Desorption experiments were conducted through five consecutive biosorption-desorption cycles, and it was determined that the desorption yield decreased to 60.80% at the end of the fifth cycle. Simulated wastewater was used to test the applicability of EMT to real water samples, and under these conditions, EMT's Cu(II) uptake capacity was found to decrease to 57.60% due to the matrix effect. As a result, EMT biomass was presented to the literature as an alternative and effective biosorbent with the advantage of easy separation from aquatic media.</p>