The paper presents the synthesis of the ligand 1-(2-hydroxyphenyl)ethanone N(4)-allyl-3-thiosemicarbazone (H
2
L)
and six coordination compounds of copper, nickel and cobalt with this ligand. The structure of thiosemicarbazone H
2
L
was studied using
1
H and
13
С
NMR spectroscopy. The synthesized coordination compounds were studied using elemental
analysis, gravimetric analysis of water content,
molar conductivity, and magnetochemistry. For H
2
L the antitumor
activity towards human leukemia HL-60 cells
and cervical cancer HeLa cells was dete
rmined. It was established that the
substitution of hydrogen atom with methyl group in the azomethinic fragment leads to the growth of antitumor activity.
