NEDO project “Fundamental Study on Rapid Evaluation Method of SOFC Durability” (FY 2013- 2017) focuses on a life time of 90,000 h with a degradation rate of 0.1 % / 1,000 h. Here, in addition to the three companies (Kyocera, MHPS, TOTO) which participated in the previous project on durability of SOFCs), three more ceramics manufacturers (NTK, NGK, Murata) have joined, and with the addition of Denso in December 2015, brings the total to 7 participating companies involved in the improvement of durability of SOFC cells/stacks. AIST, as a neutral research institute, is continuously carrying out dissectional analyses using secondary ion mass spectroscopy (SIMS) of cell stacks from each stack manufacturer before and after long-term operation in order to clarify the cumulative effect on degradation of trace impurities, which would be difficult to detect using conventional analyses. In this paper, we evaluate Impurity levels in cathodes of 7 different SOFC stacks and modules before and after long term operation.