Dipodand tetracations derived from 1-(11-mercaptoundecyl)-4-aza-1-azonia-bicyclo[2.2.2]octane bromide (1) and substituted bis(bromomethyl)benzenes have been self-assembled on a gold surface. Such SAMs are permeable to electrolytes but show some inhibition of redox processes at the electrode. Inhibition of oxidation of ferrocyanide is observed, the extent of inhibition varying with the structure of the attached species. Oxidation of bromide is enhanced, the extent again depending on the nature of the species, with compound 4, derived from 1,4-bis(bromomethyl)-2,5-dimethylbenzene, being the most efficient at both depressing oxidation of ferrocyanide and enhancing the oxidation of bromide. A model to explain these results is advanced.