Two series of cycloalkanespiro-5-hydantoins, namely cyclohexanespiro-5-hydantoins and cycloheptanespiro-5-hydantoins with a 4-substituted benzyl or a 2-(4-substituted phenyl)-2-oxoethyl group at N3 position, were synthesized and their effects on proliferation of human colon (HCT-116), leukemia (K562) and breast (MDA-MB-231) cancer cell lines were tested. For comparison, we also described the 5,5-diphenylhydantoin analogues. The structural features of the investigated compounds were characterized by elemental analysis, FT-IR, UV–Vis, 1 H and 13 C NMR spectroscopy and X-ray crystallography. Regarding their structure–activity relationships, it was shown that the substitution on the benzyl moiety with the methoxy, chloro or bromo group potentiated the antiproliferative activity relative to the parent compounds, while an increase in the size of the cycloalkyl group resulted mostly in a decrease of the antiproliferative activity. The single crystal X-ray analysis revealed the existence of dimers and chains formed by the N–H⋯O hydrogen bonds. The analysis of the molecular descriptors of Lipinski demonstrated that all investigated compounds obeyed the rule of five. To further understand their geometry and electronic structure, DFT calculations with B3LYP method using 6-311++G(d,p) basic set were performed. In this context, the UV–Vis spectra of the investigated compounds were analyzed in detail, whereby the predicted absorption spectra from DFT calculation matched the experimentally obtained ones, with a good correlation. The interesting physico-chemical and pharmacologically relevant properties of the investigated compounds warrant their further investigation. Published version: [http://technorep.tmf.bg.ac.rs/handle/123456789/4324] This is the peer-reviewed version of the following article: Lazić A, Radovanović L, Božić B, Božić-Nedeljković B, Vitnik V, Vitnik Ž, Rogan J, Valentić N, Ušćumlić G, Trišović N. Synthesis, structural characterization, DFT calculations and antiproliferative evaluation of novel spirohydantoin derivatives containing a substituted benzyl moiety. in Journal of Molecular Structure. 2019;1180:48-62. [https://doi.org/10.1016/j.molstruc.2018.11.071]