[en] The present fusion experiences are largely based on devices with graphite as first wall material. The graphite choice allows for a large operational space in all plasma scenarios, with small detrimental effect of impurities on the main plasma performance (low Z) and for power loads in transients and steady state exceeding occasionally the material limits. However, the chemical affinity of graphite with hydrogen results in large carbon erosion, migration and redeposition, which would lead to unacceptable T retention in ITER, based on extrapolation from present devices. The ITER wall material choice is determined by aim to combine the advantages of C (no melting) at the high heat flux areas, of Be on the large scale first wall (low Z) and of W on the upper divertor baffle (low erosion, large lifetime) while minimising simultaneously the critical issues of C (T retention) and of W (plasma contamination). This material choice will be tested first in the new JET ITER like wall project which serves then to define the ITER operational conditions such that they are compatible with the wall requirements and scientific goals of ITER. The wall choice in ITER is still largely determined by the possibility for detrimental conditions with respect to transient power loads, the main plasma contamination with high Z impurities and also the relatively low duty cycle and moderate amount of neutrons. In contrast, for DEMO the development of plasma control must allow the use of first wall materials that are optimised fully by the materials requirements of mechanical stability, low T retention, low erosion (large lifetime) and low activation. This is the challenge in fusion both for plasma physics and control and material physics. (orig.)