The infrared spectra of 1-chloropropyne and 1-chloropropyne-d3 have been investigated in the vapor state, in solution, and, in part, in the liquid over the spectral region 3 to 35 μ. Intensities of the infrared bands have been measured from the spectra of the solutions. The Raman spectra of the compounds in the liquid state, together with standard intensities and depolarization ratios of the Raman bands, were obtained. A complete assignment, based on a normal-coordinate calculation of the fundamentals, has been made. Coriolis coupling coefficients of three of the perpendicular-type fundamentals of CH3≡CCl were determined and those of the other two shown to be near unity. Two coupling coefficients for CD3C≡CCl were obtained. The potential function and isotope effects on Raman intensity and Raman displacement of the CCl stretching vibration are discussed.