Aldol reaction of allomaltol with arom. aldehydes, e.g., RC6H4CHO, R = H, 4-NO2, 4-F, 2-F and 3,4,5-(MeO)3C5H2CHO, gave 2-(hydroxyphenylmethyl)-3-hydroxy-6-methylpyran-4(1)-ones, maltol-derived ligands. Organometallic Ru(II)-arene complexes, [RuCl2(cymene)]2, coordinated to the maltol-derived ligands to give stable complexes and their anticancer activity against human tumor cell lines was studied. Their hydrolysis behavior and reaction with 5'-GMP was tested and compared to the parent compd. chloro[2-methyl-3-(oxo-κO)-pyran-4(1H)-onato-κO4](η6-p-cymene)ruthenium(II) (Ru-maltol). Improved stability and in vitro anticancer activity at maintained GMP binding capability were obsd., in comparison to the Ru-maltol complex.