MCFC is high-temperature fuel cell and pressurized operation is effective way to realize high performance. However, cathode material dissolves as slowly as ion in the electrolyte at pressurized operation, which are reduced to metal by H₂ in the fuel gas. These metallic particles form short-circuit bridges across the electrolyte matrix between the anode and cathode. CRIEPI has developed acceleration test method.

   On the other hand, we have carried out over 60,000 hours operation of a bench-scale MCFC and the factors of voltage degradation in relation to operating time.

   Moreover, durability test for 10,000 hours using 10kW class stacks, which have 1m² active cell area, were carried out with various gas composition under the pressurized condition.

   We also have estimated the effect of H₂S, HCl, HF, NH₃ , NOx, and SO₂ on the performance of MCFCs and behavior of these compounds, by mean of bench-scale cell tests with fuel gas containing H₂S, HCl, HF, NH₃ , NOx, and SO₂ . The acceptable concentrations of these contaminants can be calculated according to the specification of cell and the operating condition.