Imidazole and its derivatives became of interest due to their ability to bind various transition metals [1-2]. It is frequently found as part of a large number of biologically and medically significant products [3-4]. The coordination compounds of copper with a number of heterocyclic aldehyde thiosemicarbazone derivatives possess also important biological properties, such as anticancer, antimicrobial and antileukemic. This activity is directly depending of the nature of the heterocyclic moiety present in the structure, and in some cases, of the features of the anions, coordinated to the metal centers . In this presentation we describe a new coordination compound of copper with an imidazole-4-carbaldehyde thiosemicarbazone derivative. 2-methyl-1H-imidazole-4-carbaldehyde 4-ethyl-thiosemicarbazone (HL) was obtained as a result of the condensation of the 2-methyl-1H-imidazole-4-carbaldehyde with 4-ethylthiosemicarbazide by mixing alcoholic solutions of the reagents in equimolar ratio. The resulting thiosemicarbazone was analyzed with H1 and C13 RMN spectroscopy. a b Fig. 1. ORTEP representation of the crystal structure In an alcoholic solution the interaction between copper(II) nitrate and organic ligand affords the compound [CuHL](NO3)2 (Fig.1a). The organic ligand is coordinated in molecular form using for coordination the N,N,S donor set. The imidazole fragment is bound via nitrogen atom N(2). The coordination polyhedron of the copper(II) is a tetragonal pyramid. The basal plan of the pyramid is formed by the tridentate organic ligand and an oxygen atom O7 of one of the nitrate anions. An other oxygen atom of this anion O(1) is coordinated in the apical position of the neighbor molecule and ensures the formation of polymer structure, represented in Fig.1b. The second anion is not coordinated, but is involved in a network of hydrogen bounds using the hydrogen atoms from thiosemicarbazidic moiety. The crystal packing and the impact of coordination on the biological activity will be discussed.