The DFT calculations and AIMD simulations performed in this work showed that 5-FU can form a stable bond to framework-associated octahedral Al atoms. Replacement of an Al-coordinated H2O molecule by 5-FU is energetically favourable, and the octahedral environment is further stabilised by the presence of additional, non-coordinated H2O molecules that form an extended hydrogen bond network. At least for the conditions and time scales probed in the simulations, no breaking of the Al-O(5-FU) bond occurred, indicating that this coordination environment is stable at room temperature and in the presence of water. This is in stark contrast to prior observations made for 5-FU adsorbed in protonic FAU containing Brønsted acid sites, where the bond(s) between 5-FU and the framework proton(s) was (were) quickly broken if a cluster of H2O molecules was present in the vicinity. Interestingly, the qualitative difference in hydration stability is not correlated with the adsorption energies computed for water-free models, which are more negative for 5-FU interacting with framework protons. This discrepancy highlights the importance of considering competitive water adsorption when investigating different types of adsorption complexes in zeolites.