Atmospheric composition measurements from satellites are essential for monitoring the earth’s environment. The Ozone Dynamics UV Spectrometer (ODUS) will be launched on the Global Change Observation Mission (GCOM) -A1 satellite in 2006. ODUS covers from 306 to 420 nm back scattered light with 0.5 nm spectral and 20 km spatial resolution using a Fastie-Ebert type polychromator and a one-dimensional UV Si-CMOS array detector. It is a nadir-looking mapping spectrometer with a mechanical scanner, which can acquire global data in one day. It is expected to provide information about total O3, SO2, NO2, BrO, OCIO, HCHO, surface albedo, and aerosol type. Total 03 is inferred from look-up tables calculated with the radiative transfer on multiple solar back scattering. Other constituents are derived in such a way that the deviation of the measured and calculated radiance is minimized. We use the STAR (System for Transfer of Atmospheric Radiation) code for radiative transfer calculation. In recent years, tropospheric O3 measurement has become important for biomass burning and urban air pollution monitoring. The sensitivity of various O3 vertical profiles on the ODUS spectra is studied and tropospheric O3 retrieval algorithm will be presented.