The EOS Project conducted an industrial research on stationary fuel cells based on the SOFC technology developed by Siemens, through a co-operation between TurboCare S.p.A. (TurboCare, a subsidiary of Siemens Power Generation) and Politecnico di Torino. Two SOFC units (CHP 100 and SFC 5) have been installed in the TurboCare workshop. To date, the CHP 100 generator has operated in Torino for more than 16,000h, producing more than 1.5 million kWh of electric energy. After a failure of the UPS, a commercial component, the system for the first time performed a complete thermal cycle from operating temperature to ambient temperature. The shutdown has been a great opportunity of experimental analysis of the thermal cycle inside the generator. One topic has been considered: the analysis of air distribution in different sectors of the generator; this analysis gives information about the behaviour of the air cooling. The results obtained can be helpful to improve the cool down strategy in order to avoid thermal stress to stack tubes and to try to analyse the effect of the air distribution. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.