Description: We present the results of an intercomparison exercisebetween six different radiative transfer (RT) models carriedout in the framework of QUILT, an EU funded projectbased on the exploitation of the Network for the Detection ofStratospheric Change (NDSC). RT modelling is an importantstep in the interpretation of Differential Optical AbsorptionSpectroscopy (DOAS) observations. It allows the conversionof slant column densities (SCDs) into vertical column densities(VCDs) using calculated air mass factors (AMFs). Theoriginality of our study resides in comparing SCD simulationsin multi-axis (MAX) geometry (trace gases: NO2 andHCHO) and in taking into account photochemical enhancementfor calculating SCDs of rapidly photolysing species(BrO, NO2, and OClO) in zenith-sky geometry. Concerningthe zenith-sky simulations, the different models agree generallywell, especially below 90 SZA. At higher SZA, largerdiscrepancies are obtained with relative differences rangingbetween 2% and 14% in some cases. In MAX geometry,good agreement is found between the models with the calculatedNO2 and HCHO SCDs differing by no more than 5%in the elevation and solar zenith angle (SZA) ranges investigated(5 20 and 35 85 , respectively). The impacts ofaerosol scattering, ground albedo, and relative azimuth onMAX simulations have also been tested. Significant discrepanciesappear for the aerosol effect, suggesting differencesbetween models in the treatment of aerosol scattering. A better agreement is found in case of the ground albedo and relativeazimuth effects. The complete set of initialization dataand results have been made publicly available through theQUILT project web site (http://nadir.nilu.no/quilt/), enablingthe testing of other RT codes designed for the calculation ofSCDs/AMFs.