In this work, calculation of relevant thermodynamics properties, for hydrogenation reaction of aromatics compounds, was performed using the approach of molecular topology. Among the several molecular topological indexes, the molecular connectivity indexes have been used widely for calculation methods like quantitative structure properties relationships (QSPR) and quantitative structure and activity relationships (QSAR). Standard enthalpy of formation (Delta H degrees(f)), standard Gibbs free energy of formation (Delta G degrees(f)), and heat capacity at constant pressure (C-p degrees) at 298.15K for naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, tetralin, and t-decalin and equilibrium reaction constants were calculated and compared with experimental data reported in literature. Additionally, the results obtained for naphthalene, tetralin, and t-decalin were compared to those obtained from Benson's method. Results show that the thermodynamics properties calculated from molecular connectivity index presented an error less than 2% and are closer to experimental data than those from Benson's method, showing that molecular connectivity index is a promising tool for estimation of thermodynamic properties to be used in design of chemical process.