Two kinds of films, named A and B, of polydiphenylamine (PDPA) electrochemically synthesized have been characterized by ex situ resonance Raman, FT-IR and UV-vis-NIR Reflectance spectroscopies. The ex situ RR spectra of the films showed differences, that were rationalized assuming the predominance of the diphenosemiquinone aminoimine structure in the film A, while in the film B the diphenoquinone diimine segments were predominant. The variation of the nature of the film adsorbed on the electrode with the applied potential has been monitored by means of the in situ resonance Raman technique. The bands characteristics of the diphenosemiquinone aminoimine moiety are dependent on the laser power employed, being converted to diphenoquinone diimine and diphenyl diamine segments. This result was confirmed by FT-IR spectra of the film A after heating. The thermal behavior of the films was monitored by thermogravimetry (TG), derivative thermogravimetry (DTG), and differential scanning calorimetry (DSC).