The surface Li abundance was determined for a sample of 829 giant stars with accurate Gaia parallaxes for a large subsample (810 stars) complemented with accurate Hipparcos parallaxes (19 stars). Their spectra were obtained in three ground-based observatories. Three observing runs were performed at the Observatoire de Haute Provence, from 8 September to 15 September 2003 (visitor mode), from 17 January to 19 January, 2004 (service mode), and from 16 January to 16 February, 2004, service mode). High-resolution spectra were obtained with the Aurelie spectrograph attached to the 1.52m telescope. Two observing runs were performed in visitor mode at ESO- La Silla, Chile, from 3 January to 6 January, 2004, and from 5 March to 8 March, 2004. High resolution (R~43000) echelle spectra were obtained with the FEROS spectrograph attached to the MPG/ESO 2.2m telescope. Finally, a total of 92 stars were observed at the McDonald Obser vatory with the Otto Struve Telescope using the Sandiford Cassegrain Echelle Spectrometer (SES) from August 2003 to May 2004 over the course of seven observing runs. The #9 slit (1.1"x3.5") was used to yield a two pixel resolution of 60000. (7 data files).< Leer menos