The critical temperatures and pressures of nine saturated straight-chain dicarboxylic acids HOOC(CH2)(n)-COOH with n = 2, 3, 4, 5, 6, 7, 8, 10, and 12 have been measured. All of the acids investigated are thermally unstable at their critical points. The method of pulse heating of a wire probe immersed in the liquid under study has been used. Residence times are from (0.01 to 1) ms. The experimental critical properties of dicarboxylic acids have been compared with the values calculated by the group-contribution methods of Ambrose, Joback, and Reid, Constantinou and Gani, and Marrero and Gani.