1,4,8,11,15,18,22,25-Octaalkoxyphthalocy metal complexes were synthesized and spread on a pure water surface to reveal the properties of monolayer films using pi-A isotherm measurements, UV-visible absorption spectroscopy and Brewster angle microscopy. The results indicated that self-aggregation of the macrocycles occurs in monolayers spontaneously, even when no compression is applied. The mode of self-aggregation was influenced substantially by the alkoxy chain length and central metal ions.