This paper gives experimental critical temperatures and pressures of 10 n-alkylbenzenes C6H5CnH2n-1 with the number of carbons in the side chain n = 1, 2, 4, 5, 6, 7, 8, 10, 11, and 13. n-Alkylbenzenes that are heavier than butylbenzene are thermally unstable at their critical points. The method of pulse heating of a wire probe placed into the liquid under study has been used. Residence times are from (0.01 to 1) ms. Equations for the correlation of the critical temperatures and pressures of n-alkylbenzenes with the number of carbon atoms in the side chain, molar mass, and normal boiling point have been obtained. The experimental critical constants of alkylbenzenes have been compared with the values calculated by the methods of Lydersen, Joback and Reid, and Constantinou and Gani.