Potentiometric sensors based on metal oxides as electrodes and 8YSZ as electrolyte at 550 degrees C can provide selective response to C2H4 with low cross-sensitivity toward CO, H2O, C14H10 and C11H10. The target of the present work is to evaluate the influence of the material used as electrolyte, the electrolyte thickness and the working temperature to check the effect of these parameters on the response to C2H4. After surface functionalization via Ni nanoparticle deposition onto the working electrode to improve the sensor performance, the effect of 8YSZ electrolyte thickness (from 0.1 to 1.2 mm) on the sensor response was studied. The best performance was achieved with the thinner electrolyte (0.1 mm) in terms of selectivity to C2H4 and low cross-sensitivity toward CO. In second place, Ce0.8Gd0.2O2-delta (CGO) and scandium-stabilized zirconia (ScSZ) oxide-ion conductors were tested as an alternative to 8YSZ to operate at lower temperatures. ScSZ and CGO based-devices provided promising sensing performance at 450 degrees C and C2H4 concentrations below 100 ppm in dry conditions upon functionalization of the working electrode with Ni nanoparticles. At 550 degrees C, both electrolyte materials show a selective response to C2H4 with low cross-sensitivity toward CO even in wet conditions or in presence of polyaromatics. (C) 2019 The Electrochemical Society.