This is part 2 of a series of contributions by the critical properties group of the IUPAC Commission I.2 on Thermodynamics, Subcommittee on Thermodynamic Data. It presents all known experimental data for the critical constants of normal alkanes, the most extensively investigated class of organic compounds. Data are presented up to C-24, and recommendations are given along with uncertainties. Such uncertainties are relatively small for the first 10 normal alkanes, which are stable at the critical point, but are larger for the progressively more unstable C-11-C-24 compounds. The critical temperatures have been converted to ITS-90.