The infrared spectra (3200 to 600 cm-1) of gaseous vinylarsine and vinylstibine and their As-dideuteratedand Sb-dideuterated derivative were recorded at 1 cm-1 resolution. Both the infrared absorption bands of thesyn and gauche conformers of the vinylarsine and vinylstibine were observed and assigned. The integratedintensities of isolated and overlapping vibrational bands were determined experimentally. Density functionaltheory calculations at the B3LYP/6-311G(d) level were performed to obtain the values of the harmonicvibrational frequencies. The results obtained are in good agreement with the experimental spectra and helpin the assignment of the vibrational bands within the complex absorption region between 1100 and 600 cm-1.