A fuel cell system includes a fuel cell having a housing that encases the fuel cell, a supply line for a fuel cell fuel, and an exhaust gas line for fuel-cell exhaust gas. In this arrangement the supply line extends in the exhaust gas line, and the exhaust gas line encases the supply line while forming a space. Any leakage in the supply line thus results in the fuel being flushed out by means of the exhaust gases flowing in the exhaust gas line so that higher system reliability and a reduction in costs can be achieved.