The present article explores the key issues for research and development that are common to current state-of-the-art MCFC and SOFC technologies. By analyzing overlapping aspects regarding materials, operating conditions and applications of the two types of high-temperature fuel cell (HTFC), the most pressing common challenges are set forth. Similarities between the MCFC and SOFC exist especially on the anode side, given their utilization of nickel as the oxidation catalyst and their suitability for conversion of hydrocarbon fuel. Catalyst deactivation due to contaminant poisoning and carbon deposition thereby emerges as the crucial problem to overcome. A brief review of these mechanisms is given and of relevant studies in the field of HTFCs. The implications on the HTFC catalyst material given by this review are summarized and put forward as lines of research that can be undertaken jointly by players both in MCFC and SOFC development.