The characteristics of the interaction of anions with naphthalendiimides, the basic structural motif of a newly synthesized anion channel based on anion⋅⋅⋅π interactions, are studied by computational methods. Stable complexes are formed with bromide, chloride, fluoride or hydroxide anions, which exhibit strong anion⋅⋅⋅π interactions in the gas phase. Following the sequence of the polarizing power of the anions, hydroxide and fluoride complexes are the most strongly interacting. The presence of a small number of water molecules strongly affects the anion⋅⋅⋅π interactions, especially for hydroxide and fluoride complexes, so the differences in interaction strength among the anions drop significantly. The calculations suggest that a small number of water molecules can be crucial to reducing dehydration cost and contributing to stabilizing interactions with the naphthalendiimide units.