Polynuclear iron carboxylates have received considerable attention due to their importance as structural, spectroscopic and functional models of the active sites of the metalloproteins. New trinuclear Fe(III) complex [Fe3O(O2CC2H5)6(4-MeIm)3] C2H5CO2 (1) (where 4-MeIm – 4-methylimidazole) has been synthesized by the reaction of [Fe3O(O2C C2H5)6(H2O)3]NO3 with 4-MeIm in acetone solution. The structure of 1 represents the μ3-oxo-trinuclear compound with three metal atoms bridged by six propionate groups. At each axial position there is a 4-MeIm molecule (Fig. 1). The Fe(III) coordination geometry is slightly distorted octahedral, consisting of the oxygen of the central triangle, four oxygen atoms from bridging carboxylate ligands, and a terminal 4-MeIm nitrogen atom. The O(1)-Fe distances are 1.901 Å for Fe(1), and 1.903 Å for Fe(2) and Fe(3). The Fe-O(carb.) distances range from 1.982 to 2.009 Å, and Fe-N distances fall in the range of 2.083 - 2.093 Å. The presence of the uncoordinated carboxylic group of propionic acid as well as of the N−H group of 4-methylimidazole ligand results in an extensive hydrogen-bonded network in complex 1. The complex was also characterized by IR spectroscopy, mass-spectrometry and thermogravimetric analysis, and all data are discussed in the terms of known structure.figureFig. 1. The structure of compound 1.