JPH0569266B

PURPOSE:To make it possible to delay the rate and decrease the amounts of absorption of phosphoric acid moving from an electrolyte-matrix by installing the second and the third cooling plates made of different material from that of the first cooling plate among the first cooling plate in which a cooling pipe is buried, a fuel electrode and an air electrode. CONSTITUTION:When a long-term operation is carried out, an electrolyte gradually goes through water-repellent-processed electrode-base materials 2a and 2b, then reaches the second and the third cooling plates 11 and 12. A material of carbon plates touching a fuel electrode and an air electrode, that is, the second and third cooling plates 11 and 12 is selected so as to have smaller pore-diameters for delaying the rate of absorption of phosphoric acid and smaller pore volumes for decreasing the amount of absorption of it. Further, it is desirable that surface area is provided with mutually closed independent pores and volume of those pores is larger in proportion to that of total pores. Thus, it does not occur that an electrolyte-matrix is absorbed in the cooling plates quickly, and in a large amount.