The “build-up” methodology of a composite photocatalyst is a critical issue regarding the showed photocatalytic performance, including the formation of intermediates. To investigate this issue P25/WO3/Au composites were obtained by impregnation (WO3) and subsequent photoreduction (Au) with UV or visible light. The obtained composites’ photocatalytic activity and intermediate formation profiles were evaluated using phenol as a model pollutant. XPS/UPS and DRS methods were used to uncover local coordination, surface chemistry (of the different types of atoms (Ti, W, O and Au) and the band-structure (band-gap, possible electron transitions) of the obtained nanomaterials. The intermediates’ evolution profile and structural peculiarities were successfully correlated and it was shown that each minor structural (bulk or surface) change has a significant impact on the photocatalytic activity and intermediate formation dynamics.