A reference electrode including an outside wall which acts as a boundary between electrolyte and sample solution, which outside wall includes a resin which is ionically conducting, non-porous and salt-loaded, and a barrier through which no electrochemical communication between the electrolyte and sample solution is possible. A window is present in the barrier, allowing electrochemical communication between the electrolyte and the sample solution through the resin at the window. The reference electrode can be suitable for use with a separate measuring electrode, or can be combined with a measuring electrode in a single unit electrode assembly.