Interest in manganese carboxy-clusters has increased over the past few decades due to their important role as mimics of photosynthetic processes (water oxidation in photosystemII) [1] and their application as single molecular magnets (SMM) [2]. In this communication we present a μ3-oxo trinuclear mixed-valence manganese cluster with the anion of 2-furoic acid (FCA) of composition [Mn3O(FCA)6(Py)2H2O] (1). The cluster was synthesized by the reaction of Mn(II) acetate, 2-furancarboxylic acid (FCA-H), pyridine and N-n-Bu4MnO4 in ethanol. The cluster was analysed by X-ray crystallography, IR spectroscopy and cyclic voltammetry methods. The complex crystallizes in the monoclinic space group P2, and contains two independent {Mn3O} units in the asymmetric unit. Each metal ion has distorted octahedral geometry environment. The cyclic voltammogram of (1) exhibits a reversibe one-electron oxidation wave at 0.50 V vs Ag/AgCl. Using (1) as a precursor manganese oxide nanoparticles were obtained by thermal decomposition in organic phase under argon atmosphere, in the presence of olive oil and long-chain stabilizers. The materials were mainly characterised by ESEM, EDX and FTIR methods. The obtained results reveal the formation of MnxOy nanoparticles of hexagonal type.figureFig.1 Molecular structure of [Mn3O(FCA)6(Py)2H2O] (1). Fig.2 ESEM bright-field image of the manganese nanoparticles