Sentinel-4 is (S4) is a European Earth observation mission and part of the European Union Copernicus programme. The Sentinel-4 (S4) instruments will be launched on-board the MTG-S geostationary platforms, of which the first is scheduled for launch in 2024. BIRA-IASB is responsible for the development of bread-board algorithms for the retrieval of total vertical column quantities of sulfur dioxide (SO 2 ) and formaldehyde (HCHO). Tests of these algorithms on synthetic S4-spectra show that the SO 2 and HCHO algorithms are capable of retrieving the vertical column with an uncertainty of 10-15% for solar zenith angles smaller than 65 degrees, under clear-sky conditions and without the presence of aerosol.