This presentation summarises shortly the following experimental techniques: emf with liquid and solid electrolytes, vapour pressure measurements and calorimetric studies in application to metallic alloys. It is shown that usually one experimental technique is not sufficient for a reliable separation of the Gibbs energy into appropriate: entropy and enthalpy contributions, which is necessary if one seeks the correlation between thermodynamic properties and phase equilibria. Critical assessment of the data available from different sources must be performed to get the proper thermodynamic information. Several specific examples will be analysed for systems with the miscibility gap and with intermetallic compounds to demonstrate this point of view. In some cases the correlation will be extended on the physical properties of alloys as well as the structure. There are, however, some cases for which new experimental data are still needed to clarify the phase equilibria. Two examples from the field of calorimetry and emf measurements will be discussed to show how thermodynamic information must be coupled with the phase diagram investigations to obtain proper results: Calorimetric measurements. Results obtained in Cu-As and Cre-As systems will be shown and compared with existing binary phase diagrams. New data on the enthalpy of formation of solid and liquid Ge-As alloys let the description of the thermodynamic representation of the binary system be improved and express some doubts about the shape of the Ge-As phase diagram. emf studies. Results of electrochemical measurements with solid CaF2 electrolytes on Yb-Ba-Cu-O systems are analysed. This example indicates how emf results can be misinterpreted if simultaneous investigations of phase equilibria are not conducted.