A method for calculational recovery of complete molecular composition of the Fischer-Tropsch synthesis products on the basis of incomplete experimental data is proposed. The method employs VTPR equation of state for analysing the available data on the composition of gaseous and liquid phases at the exit of a Fischer-Tropsch reactor. It is shown that in most cases such data are incomplete and misleading due to both instrumental limitations and inevitable losses at phase separation manipulations. The critical thermodynamic properties of the synthesis products, as well as the parameters of the equation of state for the calculation of multicomponent equilibrium using the group contribution method are determined. The results of the calculations are displayed along with experimental data from the literature and data obtained in the laboratory and industrial scale reactors. (C) 2018 Elsevier Ltd. All rights reserved.