We have developed a new code of the Venus atmospheric chemistry based on our photochemical model already in use for Mars (e.g., Lefèvre et al., 2004). The model provides a comprehensive description of the CO₂, sulfur, chlorine, oxygen, and hydrogen chemistries with state-of-the-art kinetics data. For Venus, the code also includes a parameterized treatment of cloud microphysics that computes the composition, number density, and sedimentation rates of sulfuric acid aerosols based on observed altitude-dependant size distributions. We have coupled this photochemical-microphysical package to the LMD general circulation model of Venus (Lebonnois et al., 2010). We will describe the results obtained with this first three-dimensional model of the Venus photochemistry. The space and time distribution of key chemical species as well as the modelled cloud characteristics will be discussed and compared to observations performed from Venus Express and from the Earth. We will place particular emphasis on sulfur species, which are subject in the GCM to three-dimensional transport and convection, condensation-evaporation-sedimentation via H₂SO₄ in the cloud layer, and photochemistry above the clouds. (Lefèvre, F., et al., J. Geophys. Res., 109, doi:10.1029/2004JE002268, 2004), (Lebonnois, S., et al., J. Geophys. Res., 115, doi:10.1029/2009JE003458, 2010).