The Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard the EUMETSAT Meteosat Second Generation (MSG) geosynchronous satellites provides real time imagery in 12 spectral channels (from 0.6 µm to 13.4 µm) of the Earth full disc (every 15 min) and Europe (every 5 min), for weather forecasts and severe weather warnings. Launched on July 15 th 2015, MSG4 is the last of the MSG series; it has completed its commissioning phase and it has been placed into in-orbit storage on December 7 th 2015. As part of the commissioning activities, the radiometric performance of the instrument is tested via dedicated scans of different radiative sources, namely the Sun, deep space and the Moon. These tests are part of the Image Validation and Verification and are aimed to characterise respectively the stray-light entering the instrument baffle, the 1/f noise and the drift of the Visible and Near Infra-Red (VNIR) channels over 24 hours. This paper, introducing the basic concepts of characterisation and calibration, describes the different steps that led to the acquisition of these different radiative sources and their results assessing the imaging performance of the MSG4 SEVIRI instrument. Nomenclature B= non-linearity C = digital count DC = Digital Count