Our current understanding of Venusian sulfur chemistry remains one of the major open questions regarding the planet's atmospheric composition. The depletion of SO2 abundance in the mesosphere is evidenced by merging observations from both below and above the cloud deck. Values decrease from 130 ppmv at 30–40 km (Marcq et al., 2008) to a maximum of a few hundred ppbv at the cloud top, around 70 km (Marcq et al., 2020; Encrenaz et al., 2020, 2025; Iwanaka et al., 2025). This depletion is still not theoretically explained. The VenSpec suite of spectrometers onboard EnVision is designed to provide new observations of key gas tracers (SO2, H2O, CO etc.) in the Venusian mesosphere to help constrain its chemical landscape.Regarding modeling, while Rimmer et al. (2021) proposed increased SO2 dissolution aided by salts present in cloud droplets, most other chemical models simplify the issue by reducing the bulk reservoir of SO2 (Stolzenbach et al., 2023; Shao et al., 2020; Bierson et al., 2020). Despite this assumption, sulfur photochemistry remains complex and is linked to a delicate equilibrium between SO2 photolysis and the condensation of one of its products, sulfuric acid. To better decipher sulfur chemistry in the Venusian mesosphere, we used a chemical pathways analysis program named PaPy (Stolzenbach, 2025), based on the work of Lehmann (2004). PaPy was successfully applied to Early Mars simulations (Maurice et al., 2025), and we have extended its use to the Venus Planetary Climate Model (PCM) results.We propose to detail the most prominent chemical pathways affecting the state of SO2 in and above the cloud deck. We will focus specifically on the vertical evolution of these pathways; some are locally significant, such as the cycles involving H2SO4 production at 62–64 km, while others span a wider range of altitudes above the clouds. Finally, we will interpret these results in light of previous versions of the Venus PCM chemical system to evaluate the impact of the added nitrogen and sulfur allotrope chemistry on SO2 pathways.Marcq, E., et al. Journal of Geophysical Research: Planets 113.E5 (2008).Marcq, E., et al. Icarus 335 (2020): 113368.Encrenaz, T., et al. Astronomy & Astrophysics 639 (2020): A69.Encrenaz, T.,, et al. Astronomy & Astrophysics 703 (2025): A219.Iwanaka, T., et al. Journal of Geophysical Research: Planets 130.7 (2025): e2024JE008775.Rimmer, P. B., et al. The Planetary Science Journal 2.4 (2021): 133.Stolzenbach, A., et al. Icarus 395 (2023): 115447.Shao, W. D., et al. Journal of Geophysical Research: Planets 125.8 (2020): e2019JE006195.Bierson, C. J., and X. Zhang. Journal of Geophysical Research: Planets 125.7 (2020): e2019JE006159.Stolzenbach, A., "PaPy, a Python module for chemical pathways analysis", (2025), https://doi.org/10.5281/zenodo.17223321Lehmann, R. Journal of atmospheric chemistry 47.1 (2004): 45-78.Maurice, M., et al. Icarus (2025): 116914.