We present a description of ion transport through geometrically defined nanoslits. The description was obtained through impedance spectroscopy measurements of electrolytes with different physico-chemical parameters. The number of 50 nm high nanoslits present in each chip used for measurements could be discriminated as well as the thickness or overlapping of the electrical double layer. The zeta potential could be changed both with the pH of the electrolyte and with an external voltage to define the nanoslit conductance.