Three new calcium(II) complexes with heterocyclic alcohol (2-hydroxymethylpyridine), aldehyde (4- methyl-5-carbaldehydeimidazole) and carboxylate (picolinate, obtained in situ ) moieties were synthes- ised and characterised using elemental analysis, X-ray, IR (Raman), 1 H, and 13 C NMR methods. In addition, we compared the X-ray results obtained for calcium(II) complexes with the structures of previously described cadmium compounds, which from the chemical point of view (HSAB and Lewis acids and bases theories) can give some information for the ability of Cd 2+ to mimic Ca 2+ ions in biological systems too. The studied ligands, calcium compounds ( 1 – 3 ) and cadmium analogues were tested for their cytotoxicity against HeLa (cervical carcinoma), K562 (leukaemia) and normal cells (HUVEC) using a 3-(4,5-dimethyl- thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.