The effect of native and methylated beta-cyclodextrin on electrochemical processes of a series of nitrophenyl glycosides (o-, m-, and p-nitrophenyl beta-D-galactopyranosides, as well as p-nitrophenyl alpha-D-galacto-, alpha-D-gluco-, alpha-D-manno-, alpha-L-fuco-, and beta-L-fucopyranosides) in alkaline aqueous solutions on the mercury electrode was evaluated. The totally different influence of native and methylated beta-cyclodextrin on electroreduction of nitrophenyl glycosides was discovered. According to electrochemical measurements (cyclic voltammetry and chronocoulometry) as well as theoretical method (molecular modelling) inclusion complexes are formed between both cyclodextrins and nitrophenyl glycosides. Although the inclusion processes took place for both cyclodextrins, the source of their different influence on the electrode processes is connected with their different abilities of nitro radical anion (de)stabilisation. (C) 2013 Elsevier B.V. All rights reserved.