In this review, results of the studies of thermodynamic properties of organic substances conducted at the Chemistry Department of the Belarusian State University (Minsk, Belarus) over a period of more than 50 years are summarized. Emphasis is made on precise measurements (both calorimetry and equilibria) and prediction methods, including group-contribution, quantum chemical, and statistical mechanical, for a broad range of thermodynamic properties of various classes of chemical substances. The principal purposes of these studies were to establish relationships between thermodynamic properties of organic substances and their molecular structure, develop methods of extrapolation and prediction of the properties of substances lacking experimental data, and provide thermodynamic background for innovative energy- and resource-saving technologies.