Two p-cymenerutheniumchlorido complexes with thiourea derivative of 7-chloroquinoline (C1) and pyridine-3-imidazole (C2) were synthesized starting from [(η6-p-cymene)RuCl2]2 and corresponding ligands. The structures of complexes were determined with elemental analysis and IR, ESIMS, 1H and 13C{1H} NMR, and 2D 1H–15N correlation NMR spectroscopy. Cytotoxic activities examined by the MTT assay were performed in five human neoplastic cell lines (HeLa, K562, A549, MDA-MB-231, EA.hy926) and one nontumor human fetal lung fibroblast cell line (MRC-5). Tested complexes exhibited low micromolar activities with IC50 in the range 11.03–56.45 μM, while ligands L1 and L2 were significantly less active. Complex C1 showed cytoselective activity toward the K562 cell line (IC50 = 11.03 ± 1.39 μM) and was 3 times less active against the nontumor MRC-5 cell line. Flow cytometry analysis indicated that complexes C1 and C2 after 24 h treatment caused a concentration-dependent increase of the apoptotic sub-G1 fraction (up to 1...