Abstract <p>The dependence of the microstructural properties of copper nanowires on temperature (110, 120, and 130°C) and time (4 and 8 h) has been studied for the hydrothermal synthesis of copper nanowires using oleylamine and dextrose. The change in diameter of the Cu nanowires formed was monitored by spectrophotometry in the visible range. X-ray powder diffraction was used to confirm the target crystal structure and the absence of copper oxide impurities, as well as to show the nonlinear dependence of the average size of the coherent scattering region on the temperature and duration of the synthesis process. The scanning electron microscopy results showed that, in general, increasing the temperature and duration of the synthesis process leads to an increase in the length of the formed copper nanowires from 45 to 150 μm, i.e. under certain conditions, ultra-long structures are obtained. As a result, the aspect ratio varies from 782 to 2358 by altering the synthesis conditions. Transmission electron microscopy shows that the sample obtained at 110°C (4 h) differs from the others by the presence of particles up to 10 nm in size on the surface of the nanowires. The microstructural parameters of the obtained materials were also studied by atomic force microscopy, and the values of the electronic work function of the individual copper nanowire surface in ambient atmosphere were determined by Kelvin probe force microscopy.</p>