Thiazine dye, methylene blue forms 1:1 ion-associate with salicylic acid in aqueous phase and the ion-associate can be extracted in a series of non-polar non-coordinating solvent systems. The influence of different parameters on the process of ion-association has been studied. The suitability of a number of phenolic precursors for the formation of ion-associate with methylene blue has been tested. Charge-transfer absorption band of the dye molecules in relation to ion-pair has been followed in a sequence of neat and mixed binary solvents and the dependence of the absorption maxima has been found to correlate well with the solvent polarity. (c) 2005 Elsevier B.V. All rights reserved.