Since its launch in 1996, GOME on ERS-2 offers the possibility to observe formaldehyde (CH2O) in the UVvisible range. Global distributions of CH2O columns have been derived from the whole dataset of GOME. The retrieval process is based on a slant column fitting using the differential optical absorption spectroscopy technique (DOAS), followed by a conversion to vertical column using appropriate air mass factors (AMFs). For this latter step, best-guess profiles of CH2O, based on up-to-date emission inventories, atmospheric transport, photochemistry and wet/dry removal processes are provided by the 3D-CTM IMAGES. In operation since the end of 2002, SCIAMACHY provides nadir UVvisible radiance measurements suitable to complement GOME observations. New optimised DOAS settings are proposed in order to obtain a consistent time series combining the two instruments. We discuss the main error sources that affect the retrieval of both CH2O slant and vertical columns. Comparison with the tropospheric chemistry model IMAGES is used to investigate the consistency of the retrieved columns. Tropospheric formaldehyde is a product of the air quality service of the PROMOTEYTEMIS project (ESA\GMES Service Element Atmosphere) and of the Dragon project "Air quality monitoring and forecasting in China".