STSAT-3, a ~150kg micro satellite, is the third experimental microsatellite of the STSAT series designated in the Long- Term Plan for Korea's Space Development by the Ministry of Science and Technology of Korea. The STSAT-3 satellite was initiated in October 2006 and will be launched into a lower sun-synchronous earth orbit (~ 700km) in 2010. This paper presents a brief introduction of STSAT-3 and also introduces its secondary payload, i.e. COMIS, a compact imaging spectrometer, which was inspired by the success of CHRIS, a previous PROBA payload. COMIS takes hyperspectral images of 30m/60m ground sampling distance over a 30km swath width. The number of bands is selectable among 18 or 62. COMIS takes hyper-spectral images in two different modes: a) Pushbroom and b) multi-directional observation. The payload will be used for environmental monitoring, such as in-land water quality monitoring of Paldang Lake located next to Seoul, the capital of South Korea.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.