The asymmetric unit of the title compound, C(44)H(38)N(8) (2+)·4I(-)·4H(2)O, comprises two halves of non-equivalent cations of 5,10,15,20-tetra-kis-(1-methyl-pyridinium)porphyrin (with the full mol-ecule of each completed by the application of inversion symmetry), four charge balancing iodide anions and four water mol-ecules of crystallization (two water mol-ecules are fully occupied and four mol-ecules have a site occupancy of 50%). The porphyrin cations are arranged into supramolecular columns parallel to the b axis, mediated by π-π [centroid-centroid distance = 3.762 (4) Å] and C-H⋯π supra-molecular inter-actions [C⋯centroid distance = 3.522 (7) Å, C-H⋯centroid = 128°], leading to the formation of columns parallel to the b axis. The close packing leads to the presence of a one-dimensional channel filled with partially occupied water mol-ecules engaged in O-H⋯O and O-H⋯I hydrogen bonds.