GOCI(Geostationary Ocean Color Imager), one of three main payloads of COMS(Communication, Ocean and Meteorological Satellite), is the worlds first ocean color observation imager in geostationary orbit. It was successfully launched at Kourou Space Center in French Guiana by Ariane 5 ECA Launch Vehicle in 26 June 2010(UTC). In order to detect, monitor and predict the short-term biophysical phenomena, GOCI has six visible bands with band center 412nm, 443nm, 490nm, 555nm, 660nm and 680nm, and two near-infrared bands with band center 745nm and 865nm for the purpose of atmospheric correction. Pixel Sampling Resolution of GOCI is about 500m at the center of the GOCI coverage area. The size of GOCI coverage area is the 2,500km×2,500km square, and the location of the coverage center is at 36˚N and 130˚E. GOCI coverage area is composed of 16(4x4) slot images. Because GOCI equips 2D CMOS with 1413 x 1430 effective pixel array, GOCI IFOV corresponds to the FOV of GOCI slot area. GOCI also has been developed to observe the GOCI coverage area by every hour and planned to observe and transmit 8 GOCI coverage area images per day. The mission life time of the GOCI is about 7 years after In-Orbit Test(IOT).GOCI user requirements was derived from Korea Ocean Research & Development Institute(KORDI), and GOCI was co-developed by Korea Aerospace Research Institute(KARI) and EADS Astrium in France followed by the KORDIs user requirementsAt this moment, GOCI is under the In-Orbit Test operation. GOCI functional test to verify the operability of GOCI was successfully accomplished, and GOCI radiometric and geometric tests are on-going. In parallel, operation test and verification of GOCI ground processing system equipped in KOSC are on-going without any major issue. In this paper, we present the overall status of GOCI including preliminary results of GOCI In-Orbit Test.