The effect of the structural change of the Ni-Cr anode and the electrolyte re-distribution among the components during the MCFC operation upon the change in the cell performance was investigated through a long-term operation using the single cell with an effective electrode area of 100cm². Two types of Ni+10w/oCr anode, which were fired at 700℃ and 1,000℃ for 30 minutes under the reduction atmosphere, have been used. The single cell with the anode fired at 1,000℃, showing good resistance to sintering and creep and less formation of micro-pores, was successfully operated for 5,200 hours with no significant decay of the cell performance. The performance of the cell at the current density of 150mA/cm² was 0.83V at the beginning and 0.77V at the operation time of 5,200 hours, and the average decay rate of the cell performance during the operation was about 11.5mV/1,000hr. In the single cell operation using the anode fired at 700℃, however, the rapid degradation of the performance was observed at the operation time of 800 hours. This was because the structural changes of the anode occurred due to sintering and creep, which resulted from a small amount of Cr solid solution in the Ni phase because of low firing temperature. It was also because the lithiation of Cr or Cr₂O₃ of the anode into LiCrO₂ formed so large amount of micro-pores as to redistribute the electrolyte from the matrix to the anode, resulting in the deficiency of the electrolyte in the matrix.