In supplying more experimental material on the Hofmeister (or lyotropic) series on the effect of inorganic anions on the solubility of proteins and nonionic micelles in water, we studied the effect of inorganic and organic acids and bases on the phase diagrams of binary water-nonionic amphiphile mixtures, as well as on those of ternary water-oil-amphiphile mixtures (microemulsions). We found that acids make nonionic amphiphiles effectively more hydrophilic. With inorganic acids, the effect increases with increasing acidity; with weak organic acids, however, it increases with decreasing acidity. A strong inorganic base such as NaOH, on the other hand, makes nonionic amphiphiles effectively less hydrophilic, whereas a weak organic base such as formamide has an opposite effect. The application of dicarboxylic acids, in particular, for lowering the mean temperature of the three-phase bodies in ionic sodium bis(2-ethylhexylsulfosuccinate) (AOT)-microemulsions is briefly discussed.