The axial Zn2GeO4/ZnO nanowire heterojunction was successfully synthesized via chemical vapor deposition (CVD) approach. The transmission electron microscopy (TEM) study revealed that the growth follows the vapor-liquid-solid (VLS) mechanism with an orientation relationship of (3 0 0)(Zn2GeO4)//(-1 1 0)(ZnO) and (0 0 3)(Zn2GeO4)//(1 1 0)(ZnO), in which a small lattice mismatch between Zn2GeO4 and ZnO was observed. The ZnO segment grows out axially along Zn2GeO4 ternary nanowire and its length can be tuned from tens of nanometers to over 10 pm by adjusting the ZnO source supply. This ternary/binary nanowire heterojunction shows a diode effect via nano-manipulators in-situ measurement under field emission scanning electron microsocpy (FESEM). (C) 2010 Elsevier B.V. All rights reserved.