The interaction of pillar[5]- and pillar[6]arenes with gaseous NO2/N2O4, and with alkyl nitrites in the presence of a Lewis acids in organic solvents has been studied. Experimental data support the reversible formation of inclusion complexes between pillararenes and nitrosonium cations. Upon the prolonged standing on the reaction mixture the degradation of pillararene macrocycles has occurred as a result of nitration/ pillararene macrocycle degradation products.