In search of benzamidoxime (BHam) derivatives that provide a single Tc-99m-labeled compound of high in vivo stability, we synthesized three N-alkyl compounds of benzamidoxime (BHam) ligand. They provided a single Tc-99m-labeled compound by ligand exchange reaction of Tc-99m-glucoheptonate in high radiochemical yields (over 95% at MBHam concentration of 1 x 10(-5) M). Tc-99m-N-methyl benzamidoxime (Tc-99m-MBHam) showed higher stability than the parental Tc-99m-BHam. The complex of this compound with (TcO3+)-Tc-99g ion was prepared, isolated, and characterized by FT-IR and NMR spectra as well as X-ray diffraction. Tc-99g-MBHam crystallized in an orthorhombic space group Pna2(1) with a = 13.4823(5), b = 15.5410(7), c = 7.7907(3) angstrom, V = 1632.39(11) angstrom(3), and Z = 4. The Tc-99g complex possessed square base pyramid coordination geometry. The equatorial plane was formed by two-amine nitrogen and two-oxime oxygen atoms in trans position, while the oxo core of the technetium(V) occupied the apical position. The Tc-99g-MBHam proved to be identical with the Tc-99m-MBHam prepared at the no-carrier-added level by comparison of their HPLC profiles.