Ferrocene (bis(η5-cyclopentadienyl)iron(II)) is an important member of metallocenes, organometallic compounds whose derivatives are intensively studied as potential candidates for tumor treatment. A promising strategy that could potentially overcome the disadvantages of the widely used chemotherapeutic agent cisplatin is the synthesis of heterobimetallic complexes that, in addition to ferrocene, have another metal in their structure. In this graduation thesis, the biological activity of two newly synthesized heterobimetallic complexes of nickel with aminoferrocene ligands was examined. The mentioned complexes were selected for further testing from the original 20 synthesized compounds with the ferrocenyl moiety, due to their stability and significant toxicity for human cervical carcinoma HeLa cells as tested by the MTT assay. Using the same method, the cytotoxicity of the selected complexes was tested on tumor cell lines MES-OV, RPMI-7951, MDA-MB-435 and on a normal cell line. Both complexes were less toxic for normal than for tumor cell lines, which indicates their selective action. Using specific inhibitors and precursors of glutathione synthesis, it was shown that glutathione was not involved in cell stress response caused by both complexes. Flow cytometry showed that both complexes stimulated the accumulation of cells in the G0/G1 and S phase of the cell cycle and caused apoptosis. Using the Western blot method, it was determined that treatments with the selected complexes did not cause cleavage of the PARP-1 protein, a specific marker of apoptosis, and that increasing the concentration of both complexes led to a decrease in the expression of the antiapoptotic protein Bcl-2.