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The electrolyte supported cells satisfy the requirements for the application in the solid oxide fuel cell such as mechanical stability, long-term stability during operation at temperatures <1000{degree sign}C, thermal cycling and very low degradation during repeated anode reduction/oxidation cycles. Nevertheless an enhancement of the power density at T=800-850{degree sign}C should be achieved to increase the power density level towards anode supported cells. The electrolyte supported solid oxide fuel cells on dense 8YSZ or 10Sc1CeSZ tapes (50x50x0.150 mm) with screen printed nickel oxide and yttria stabilized zirconia cermet anode (NiO/YSZ) and lanthanum strontium manganite and yttria stabilized zirconia composite cathode (uLSM/YSZ) were sintered in co-firing. The long-term tests (over 1000 hours) were carried out at 850{degree sign}C at constant load of 550 mA/cm2 (H2:H2O:N2=40:5:55, fuel utilization uf=50%) for 8YSZ based MEA and 650 mA/cm2 (H2:H2O=50:50, uf=23%) for 10Sc1CeSZ based MEA. During the redox cycle the cells were unloaded and fully oxidized by air for 120-180 min. Up to 10 redox cycles were performed. The field emission scanning electron microscopy (FESEM) was used to characterize the microstructural changes that occurred after long-term and redox cycles experiments. Changes of polarization resistance of the cells during the experiments were analyzed by impedance spectroscopy.