In studying ion-selective membrane electrodes, the experimental techniques may be grouped according to the nature of information required: methods providing information on the electrical properties of ion-selective membranes; methods used for the investigation of individual processes regarded decisive in respect to the dynamic properties of ion-selective electrodes; and methods used to study the phenomena at the membrane-solution interface. The different techniques are equally relevant for the interpretation of the response mechanism of ion-selective electrodes. The correlation studies between the dynamic response of ion-selective electrodes (ISE) and the kinetics of dissolution of the active material of solid-state ion-selective membranes contributed greatly to the interpretation of the transient functions of ISE. In most analytical applications of ISE, the transient function of the measuring system is determined primarily by the properties of the electrochemical cell with the exception of electrodes of extremely high internal resistances.