The infrared spectra of the isostructuralMVO3 compounds (M=K, Rb, Cs, Tl, NH4), consisting in an array of infinite tetrahedral chains, are reported and discussed with the aid of a simplified factor group analysis. In the case of NH4VO3 also the laser-Raman spectrum was recorded and analyzed. Force constants, mean amplitudes of vibration and other bond properties for the terminal VO2 groups, as well as for the VOV chain units are estimated.