Since 1995 GOME-1 is measuring ozone (total column and profile), nitrogen dioxide and other minor trace gases on-board of ERS-2. An advanced GOME-2 instrument will fly on the METOP satellites. The GOME-2 measurements will provide the input for the ozone data record in the timeframe 2005 to 2020 provided by the EUMETSAT Polar System. The on-ground calibration of the instrument encompasses spectral, absolute radiance and irradiance calibrations as well as polarization, straylight, and slit function characerization. Main results of the first flight model are discussed.