The POLDER instrument is a wide field of view radiometer designed to measure the polarization and the directionality of the solar radiation reflected by the Earth-atmosphere system, in the visible and near infrared spectrum. The original instrument concept of POLDER results in the capability of observing over a single pass any target within the instrument swath under up to 13 different viewing angles. For each viewing angle, the target is imaged in 8 narrow spectral bands, and for 3 of these channels at three different polarization angles. The multi-mission scientific objectives of POLDER lead to severe radiometric and geometrical requirements; this paper describes the POLDER instrument characteristics and the pre-flight performances measured on the flight model. Developed by CNES, the French space agency, POLDER is installed on the ADEOS platform developed by NASDA, the Japanese space agency. It will be launched in August 1996.