X-ray photoemission and magnetometric studies of valence changes in Ce(Cu1−xNix)4Ga

► Ni substitution for Cu in CeCu4Ga leads to the loss of Ce 4f states localization. ► Valence fluctuations visible in the XPS of Ce 3d states. ► Magnetic susceptibility measured and the valence resolved up to 1000 K. ► Importance of the temperature independent susceptibility