PEO(n)LiCF(3)SO(3) and PEO(n)Cu(CF3SO3)(2) with varying composition of n = 8-128 have been studied using X-ray Photoelectron Spectroscopy (XPS). The binding energies for various core levels of the elements present in these polymer electrolytes and their observed chemical shifts are obtained for different salt concentrations. It is shown that the interaction between PEO and each salt is based on a complexation between the ether oxygen of PEO and the cation of the salt as well as an effective cross-linking between the polymer chains of PEO through the anion of the salt. While in PEO there is only one type of carbon atom, the above interactions in salt added PEO system have lead to the formation of different inequivalent carbon configurations. The observed variations of intensities of various peaks with increased salt concentration are interpreted in terms of varying coordination of the elements present in these polymer electrolytes and their varying strength of interaction. The usefulness and limitations of XPS to unravel the complicated structural aspects in these materials has been demonstrated.