The velocity of sound in liquid CF4has been measured in the temperature range from its triple point to its normal boiling point. Measurements have been made with an ultrasonic interferometer, consisting of barium titanate ceramic in tubular form, to an accuracy of 0.4% or better. The adiabatic compressibility has also been calculated for the corresponding temperature range using available density data. No other velocity of sound or compressibility data for CF4are available for comparison. Comparisons with other liquids by the method of corresponding states show similarity between CF4and CCl4, but not between CF4and methane or argon.