Cathodic protection (CP) conditions of a metallic structure are verified by checking that the protection potential matches the protection criteria. Nowadays commercial probes are available to perform correct potential reading eliminating the ohmic drop contribution. In this paper a new probe with zinc reference electrode is proposed. Indeed zinc is a promising material when is in active condition due to the low overpotential and the high exchange current density. Laboratory tests were carried out to select the composition of the backfill of the probe and to verify the stability of zinc during continuous monitoring of CP. As regard the backfill mixtures of gypsum-clay-cellulose and additives were tested with water absorption electrolytic conduction and weight loss tests. Two mixtures were adopted to prepare potential probes with zinc reference electrode. CP tests were performed in soil-simulating environment for 40 days. Tests indicated that zinc reference electrode shows a good stability during continuous monitoring of the protection potential of the steel coupon.