The paper presents experimental critical temperatures and critical pressures of thermally unstable alk-1-enes CnH2n with a number of carbon atoms n = 13-20. The method of pulse heating of a wire probe placed in the liquid under investigation has been used. Equations for correlation of the critical temperatures and pressures of alk-1-enes with a number of carbon atoms in a molecule have been obtained. The acentric factors of alk-1-enes have been calculated. (C) 1999 Elsevier Science B.V. All rights reserved.