We have used action photofragmentation spectroscopy in the visible spectral range (410 to 650 nm) to investigate the optical properties of different monomeric and dimeric M-(II)-meso-tetra-(4-sulfonatophenyl)-porphyrin (with M = Pd(II), Cu(II), Zn(II)) multianions isolated in the gas phase without solvent. In particular, we report the position of the Q-bands (S-0 -> S-1 transitions) as a function of charge state, counterions, oligomerization, and dimer structure type. The results for the monomers (charge states = 4- and 3-, sodiated and protonated) are in good agreement with TDDFT calculations and condensed-phase spectra. For both homo and heterometallic dimers, photofragmentation spectra were recorded for two charge states, 5- and 3-, corresponding to coplanar and cofacial structure types, respectively. The fragmentation patterns observed for the dimers depend significantly on charge state, with fragmentation into monomers being dominant for the 5- species, while the 3- charge state predominantly fragments by SO2 loss. The monomer -> dimer Q-band spectral shifts observed in the gas phase were compared with the optical properties of porphyrin aggregates in solution.