Ni-Cu alloy nanowire array, with uniform length and diameter, was well fabricated by using alternating current electrodeposition. Both X-ray diffraction and in situ heating extended X-ray absorption fine structure technique were employed to characterize its structural change with temperature. As expected, a weak concentration fluctuation of Ni and Cu atoms was found in the as-prepared nanowires. However, this concentration fluctuation can be easily eliminated by heating the as-prepared sample at 200 degrees C, which resulting in an approximately homogeneous Ni Cu solid solution. From the nanostructural point of view, the serviceability temperature of Ni-Cu alloy nanowire array in magnetism could not exceed 200 degrees C. The Ni-Ni, Ni-Cu and Cu-Cu bonds were found to have different thermal expansion behaviors, causing the distortion of the crystal cell. An average thermal expansion coefficient (1.1 x 10(-5) K-1) was obtained. The structural change of Ni-Cu alloy nanowires with temperature was discussed. (C) 2010 Elsevier B.V. All rights reserved.