Al4SiC4 is a new semiconductor with numerous potential technological applications. We report here the first thorough experimental Raman and Infrared (IR) investigation of vibrational properties of Al4SiC4 single crystals grown by high temperature solution growth method. The experimental results are compared with the full theoretical analysis of vibrational properties based on Density Functional Theory calculations that are revisited here. We have obtained a good agreement between the experimental and calculated Raman phonon modes, and this allowed the symmetry assignment of all the measured Raman modes. We have revisited the Density Functional Theory calculation of the IR active phonon modes and our results for LO-TO splitting indicate a substantial decrease of ΔωLO − TO compared with the previous reported calculation. Moreover, most of the IR modes have been symmetry assigned from the comparison of the experimental IR spectra with the corresponding Raman spectra and the Al4SiC4 calculated phonon modes.