Phthalocyanines (Pc) are synthetic compounds of interest in various fields. However, their high hydrophobicity promotes the undesirable aggregation process in aqueous media. Studies carried out with aluminum phthalocyanine hydroxide (AlPcOH) in different water/ethanol mixtures (v/v) have shown that in proportions of water lower than 30% the Pc is in the monomeric form. At 40 and 50% water/ethanol there was formation of dimers linked by hydrogen bonding or Al-O-Al bridged, while in percentages of water higher than 60% the aggregation process is complex, with multiple equilibria and higher-order aggregates (J-type).