In this article, we investigate the vibrational properties of a series of pi-conjugated alpha,alpha＇-bis(aminomethyl)-oligothiophenes, in the pristine state, as solids. The FT-IR and FT-Raman spectra have been studied in relation to the effective conjugation length of the compounds. We have used ab initio calculations, at the B3LYP/6-31G** and RHF/6-31G** levels, as a support of the experimental analysis. Our study reveals that the aminomethyl end groups easily undergo a protonation process upon reaction with atmospheric moisture, although this does not affect the electronic structure of the pi-conjugated spine. This structural characteristic of these oligothiophenes brings new practical applications for possible technological developments.