In the search of new therapeutic tools for the treatment of American Trypanosomiasis, the largest parasitic disease burden in the American continent, three series of novel ruthenium complexes of the formula [RuCl2(HL)(2)], [RuCl3(dmso)(HL)] and [RuCl(PPh3)(L)(2)] with bioactive 5-nitrofuryl containing thiosemicarbazones; as ligands (HL neutral, L monoanionic) were synthesized and characterized. Their in vitro growth inhibition activity against Trypanosoma cruzi and the effect of co-ligands in related physicochemical properties i.e. nitro moiety redox potential, lipophilicity and free radical scavenger capacity were evaluated. Results show that although a loss of activity was observed as a consequence of ruthenium complexation, lipophilicity and free radical scavenger capacity of the obtained complexes could be correlated to their trypanocidal effect. (C) 2009 Elsevier Masson SAS. All rights reserved.