Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to study ions depth profiles across ion–selective membranes. Advantageously, this approach does not require incorporation of additional components (e.g. chromoionophore) in the membrane composition, compared to that used in typical potentiometric applications. Moreover, comparison of ions distribution in differently pretreated membranes is possible. Concentration profiles of primary and interferent (Na+) ions were recorded, on example of Pb2+-selective poly(vinyl chloride) based membrane. It was found that the contents and the distribution of Pb2+ and Na+ ions across the membrane is strongly dependent on composition of the solutions to which both sides of the membrane were exposed during preconditioning and on the plasticizer included in the membrane formulation. On the basis of concentration profiles, primary ion diffusion coefficients in both membranes were calculated, and the value obtained for o-NPOE containing membrane was found to be about 2 times higher than for DOS plasticized counterpart. Using LA-ICP-MS, ion concentration profiles and their evolution in galvanostatically polarised solvent polymeric poly(vinyl chloride) can visualized. Thus different effects depending on the lipophilic salt cation in the membrane and pre-conditioning solution applied can be followed.