Meteosat Second Generation (MSG) is a series of 3 (possibly 4) geostationary satellites developed and procured by the European Space Agency (ESA) on behalf of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). The first satellite (MSG-1) was launched on 29th August, 2002 by an Ariane 5 rocket. After the LEOP and the drift to the commissioning longitude, the satellite was positioned above the Atlantic Ocean at 10.5° W (longitude) with a 1.9° orbital inclination. The prime contractor of MSG satellite series is Alcatel Space Industries (France) and the Imaging Radiometer SEVIRI is procured under the responsibility of Astrium SAS (France). The MSG-1 satellite commissioning is performed by EUMETSAT with the support of ESA and industry. MSG-1 commissioning started on 25th September 2002. This paper addresses the results of the SEVIRI functionality tests performed as part of the MSG-1 commissioning and describes the radiometric and imaging performances of the main optical payload SEVIRI, including the image quality after its rectification and calibration. The performance results presented here are based on an offline analysis of a limited subset of the large amount of SEVIRI data obtained during the MSG-1 commissioning tests.