Three new homopolynuclear complexes with azido bridges have been obtained by using [Cu(AA)(BB)] + building-blocks (AA=acetylacetonate; BB=1,10-phenanthroline or 2,2′-bipyridine). The reaction between [Cu(acac)(phen)(H 2 O)](ClO 4 ) and NaN 3 leads to a mixture of two compounds: a binuclear complex, [{Cu(acac)(phen)} 2 (μ 1,3 -N 3 )](ClO 4 )·2H 2 O (1), and a linear tetranuclear one, [{Cu(acac)(phen)(ClO 4 )} 2 {Cu(phen)(μ 1,1 -N 3 ) 2 } 2 ] (2). The reaction between [Cu(acac)(bipy)(H 2 O)](ClO 4 ) and NaN 3 affords also a mixture of two compounds: [{Cu(acac)(bipy)} 2 (μ 1,3 -N 3 )] 3 (ClO 4 ) 3 ·3.75H 2 O (3) and [Cu(acac)(bipy)(N 3 )][Cu(acac)(bipy)(H 2 O)](ClO 4 ) (4). The X-ray crystal structures of compounds 1–4 have been solved (for compound 4 the crystal structure was previously reported). In compounds 1 and 3, two {Cu(AA)(BB)} fragments are bridged by the azido anion in an end-to-end fashion. Two isomers, cis and trans with respect to azido bridge, were found in crystal 3. The structure of compound 2 consists of two Cu(II) central cations bridged by two μ 1,1 -azido ligands, each of them being also connected to a {Cu(acac)(phen)} fragment through another μ 1,1 -azido ligand. The cryomagnetic properties of the compounds 1 and 2 have been investigated and discussed. The magnetic behaviour of compound 1 shows the absence of any interactions between the metallic ions. In the tetranuclear complex 2, the magnetic interactions between the external and central copper(II) ions(J 1 ), and between the central metallic ions (J 2 ) were found ferromagnetic (J 1 =0.36cm −1 , J 2 =7.20cm −1 ).