A platform for the multiplexed control of chemical reactions with acidity, requires reaching high proton concentrations and being able to maintain the contrast between the acid and alkaline regions in miniaturized spaces during times much longer than the characteristic diff usion and reaction times. It also requires an accurate control of the proton concentration in aqueous and organic solvents to allow diff erent chemical strategies including the possibility to control quantitatively the acidity f or orthogonal control of chemical reactions at diff erent acidities. Finally, while the quantif ication of acid in aqueous environments is well predicted by the well-known proton dissociation constants (pK a expressed in logarithm scale), in organic solutions, the proton activity is more elusive to determine. In these solvents the pK a of the conjugated acid/base pairs depends also on their interaction with the solvents, and the possible proton carriers that may be added to f acilitate the dissociation, or as in the case of electrolytes, to change the properties of the solution . A good control in organic solvent for the generalization of chemical reactions requires the generation of a neutral acid f rom electrodes that would avoid aff ecting the chemical reactions of the electrolyte while preserving their degradation. Such acid can be used as a ref erence f or the determination of pK a values in organic solvents.