Electron beam co-evaporation is one of the ex situ techniques being developed for cost-effective fabrication of YBa2Cu3O7-δ (YBCO) coated conductors. To achieve high critical current (Ic) and fast conversion, further understanding is needed of the chemical and microstructural characteristics of the precursors and the phase evolution process towards the epitaxial c-axis oriented YBCO film during the post-deposition conversion annealing. In this study, X-ray photoelectron spectroscopy (XPS) was used to investigate the chemical and compositional profiles of the precursors. Samples quenched from the processing stage were also inspected for identifying the transient elemental chemical states during the YBCO phase formation. XPS survey and detailed spectra were recorded for the surfaces and through various depths. It is suggested that XPS spectra, especially the “Auger parameters” can be used for revealing the conversion reaction. Preliminary results indicate that the copper oxidation state might have important effect on precursor conversion behaviors.