A wide variety of mechanisms can be proposed to describe a given electrochemical reaction. Before measuring the parameters of a mechanism, it is necessary to check whether it is theoretically possible to do so. The question arises as to whether a given mechanism can accurately reproduce experimental results for different sets of parameter values. Another question is whether several mechanisms may exist which can reproduce experimental results with the same accuracy. The concepts of identifiability and distinguishability are used in systems theory to study the structural properties of models. These concepts are applied to reaction mechanisms proposed for the interpretation of experimental results obtained using steady-state investigations and electrochemical impedance spectroscopy in the field of metal dissolution and passivation.