Wall conditioning of fusion devices is an effective means for controlling the fuel recycling and the impurity generation due to plasma­surface interactions. Techniques used are baking of in-vessel components, Glow-Discharge Cleaning (GDC) and thin film deposition on Plasma Facing Components (PFCs). The largest existing tokamak JET with its new ITER-Like Wall provides a unique experience to study the wall conditioning in the presence of beryllium and tungsten PFCs and to compare with the extensively studied carbon dominated PFCs. The analysis of the initial conditioning cycle of JET after ILW installation is presented in the first part of this paper. Monitoring of impurities throughout the ILW campaign is analysed in the second part. A study of the poloidal glow discharge wall current distribution as a function of the electrode number, glow current and deuterium pressure is presented in the last part and the results are extrapolated to ITER.