For high temperature fuel cells in combined heat and power applications, it is generally assumed that a stack lifetime of at least 40,000 h is required in order to achieve cost-of-electricity targets. From existing experience, it is known that lifetime limiting issues for molten carbonate fuel cell (MCFC) systems are mainly materials issues of the stack. An overview is given of the most critical endurance issues of the MCFC stack. In addition, it is argued that under specific operating conditions of the system, the stack is expected to have lifetimes over 40,000 h with the use of state-of-the-art materials, based on model calculations. Clearly, the estimated endurance data need to be verified by long-term stack and system tests.