The new coordination compounds based on copper(II) salts: [Cu(L)Br], [Cu(L)H2O]ClO4 were obtained, where HL is N-[4-({2-[1(pyridin-2-)ethylidene]hydrazinecarbothioyl}amino)phenyl]acetamide. The thiosemicarbazone HL was characterized by FT-IR, 1H NMR, and 13C NMR spectroscopy. All copper(II) coordination compounds were characterized by elemental analysis, FTIR, EPR spectroscopy, and molar electrical conductivity. Furthermore, single crystal X-ray diffraction analysis elucidated the structures of HL as well as complexes. The aim of the present investigation is the study of antioxidant activity (AOA) and toxicity to Daphnia magna of the tested coordination compounds. The thiosemicarbazone-type ligand HL containing a paracetamine (4-Aminoacetanilide) and all complexes exhibit remarkable AOA, surpassing the activity of Trolox. The HL demonstrates an AOA that is four times higher than that of Trolox. [Cu(L)Br], [Cu(L)H2O]ClO4 showed AOA against ABTS•+ with IC50 values 32.4±1.6 and 10.1±0.3 μM, respectively. To determine the toxicity of the tested compounds, the immobilization test on the crustacean D. magna was conducted following a European Standardized Methodology. [Cu(L)Br], [Cu(L)H2O]ClO4 exhibit toxicity with LC50 values 1.0 ± 0.1 and 65.4 ± 11.8 μM, respectively. Funding: This research was funded by ANCD, grant numbers 20.80009.7007.12 and 20.80009.5007.10.