In partnership with the European Commission and in the frame of the Copernicus program, the European Space Agency (ESA) is developing the Sentinel-2 optical imaging mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a satellites constellation offering a unique combination of global coverage with a wide field of view (290km), a high revisit (5 days with two satellites), a high spatial resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands in visible and shortwave infra-red domains). The Centre National d’Etudes Spatiales (CNES) supports ESA/ESTEC to insure the Calibration/Validation commissioning phase during the first three months in flight, providing refined Ground Image Processing Parameters and leaving then the floor to the ESA operational processing center after the commissioning phase. This paper provides an overview of the Technical Expertise Center Sentinel-2 (TEC-S2) which is the CNES expertise center in charge of the Calibration/Validation activities during the In Orbit Tests. It describes first the functional breakdown and the IT architecture put in place, regarding to the Sentinel 2 calibration needs and depending on CNES organization. A focus is made on software reuse and also on the parallelization of tasks processing voluminous data. Indeed, the significant 290 km swath image products, associated with the 13 spectral bands and the 12 detectors of the specific focal plan constitute a good opportunity to implement new software configurations. Then, as a second step, it provides the first feedbacks on the operations carried out by this center and in particular the first results on data processing performances.