Based on thermodynamic perturbation theory of Wertheim, statistical associating fluid theory (SAFT) has proven to be quite successful in the prediction of thermodynamic properties of polar and non-polar fluids. In this work, a new version of SAFT (modified SAFT BACK) equation of state has been developed to determine the speed of sound for some chain fluids (from C-1 to C-10) in the wide density and temperature ranges including critical temperature. We have also calculated the isobaric and isochoric heat capacities over the wide density and temperature ranges, including liquid and supercritical regions. Moreover, we have investigated the different microscopic contributions to the isochoric heat capacity. The ability of the modified SAFT BACK EOS to predict the speed of sound and heat capacities of chain fluids near and far from critical regions is discussed. (c) 2006 Elsevier B.V. All rights reserved.