Vibrational Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of a few alpha,alpha’-dimethyl end-capped oligothiophenes with increasing chain length (from the trimer up to the hexamer) in solution are collected. Relevant data are interpreted with the help of the assignment of the LR and Raman related bands of the solid samples. The aim of the work is to extract from the comparison of both series of spectra (solutions and solids) structural probes for conformational disorder and mean pi electron conjugation lengths in solution.