Nitric oxide (NO) is an extremely toxic compound formed during combustion, predominantly at high temperatures, and it is among the most important atmospheric pollutants. However, this compound has interesting biological activities, since it can control important biological processes in living organisms. With the aim of developing new materials that can be used as selective chemical sensors or as biomedical NO delivery agents we carried out a quantum mechanical study of the interaction of NO with aluminum phthalocyanine (AlPc) at B3LYP/6-31G* level. The calculation results show clearly that the complexation of NO with AlPc depends on the latter's oxidation state. NO is more strongly bonded to AlPc in the reduced state (-33.77 kcal/mol) than in the oxidized state (-4.96 kcal/mol). By applying the Fukui function and analysis of the Frontier molecular orbital, it was possible to explain the situation within which nitric oxide interacts with AlPc.