The UV spectral lines formed at transition region temperatures in the solar atmosphere, shows a prevailing redshifted emission. Using the Solar Ultraviolet Measurements of Emitted Radiation spectrometer flown on the Solar and Heliospheric Observatory spacecraft, we measure the amount of line shift as a function of the temperature for several spectral lines formed in the range between 10^{4} and 10^{6} K. We analyze spectrograms relative to the quiet Sun and to the active region NOAA 7946. The velocities derived are increasing from a redshift of ~ 0 km s^{-1} at ~20000 K to 10 km s^{-1} at 1.910^{5} K for the quiet Sun, and to ~ 15 km s^{-1} at 10^{5} K for the active region. At higher temperature an opposite behaviour is observed. In the quiet Sun a blueshift of ~ -2 kms^{-1} is observed at the Ne VIII formation temperature (6 10^{5} K), while in the active region, a blue-shifted value around -8 kms^{-8} is observed for the same spectral line. The finding a blueshift in NeVIII is due to the adoption of a new rest wavelength of 770.428 A. By 10^{6} K the blueshift is ~ -10kms^{-1} in the active region as measured by Fe XII 1242.