In the present work, we investigate the electron transfers occurring in the porous void of three MFI-type zeolites (ZSM-5) nanomaterials (nanocrystals, nanosheets and nanosponges) after adsorption and photoexcitation of t-stilbene (t-St). ZSM-5 nanosheets are constituted of lamellar stacking of several nanosheets (20-40 nm) where each nanosheet have a thickness of 2 nm. Nanosponges are composed of ZSM-5 nanocrystals (2-3 nm) separated by mesoporous holes of 5.8 nm in such a way to obtain hierachical materials. While the nanosheets show a microporosity similar to that observed for ZSM-5 nanocrystals, the absorption isotherms of the nanosponges show the existence of a secondary microporosity. After photoirradiation of t-St, UV-vis absorption spectroscopy shows the formation of charge separated states (Radical Cation and Charge Transfer Complex) in the nanocrystals and in the nanosheets whereas no ionized species is detected in the nanosponges. Radical Cation (RC) is stabilized in nanosheets while it evolves very rapidly towards a Charge Transfer Complex (CTC) in nanocrocrystals. The particular morphology of the nanosheets and nanosponges is put forward to explain this result since all host materials are of MFI-type. To investigate ultra-short phenomena in the three nanomaterials, UV-vis transient spectra were recorded between 2 and 450 μs after photoexcitation by nanosecond laser pulses. In nanocrystals and nanosheets only the RC is detected whereas CTC formation is not observed. Photoexcitation of t-St in nanosponges also leads to the formation of RC but it recombines completely within 70 μs. This suggests the preferential location of t-St in the secondary microporosity with pores larger than the micropores of the MFI-type framework and possibly in the mesopores of the nanosponge.