The formation equilibria for the binary complexes of Cu(II), Ni(II), Co(II), Zn(II), Mn(II), Hg(II), Cd(II), Ca(II), and Mg(II) with cefadroxil (Cef) and for the ternary complexes Cu(Cef)(L), where L refers to amino acid or DNA, were investigated. The protonation constants of cefadroxil and formation constants of the formed complexes were determined at 25 degrees C and mu = 0.1 M NaNo(3). Cooper(II) and cobalt(II) complexes of cefadroxil were isolated in solid state and characterized by elemental analysis, infrared and electronic spectral, conductivity and magnetic measurement.