Development plans for hard-to-recover hydrocarbon reserves, which include deposits of high-viscosity oils, are of particular relevance for the development of the Russian oil industry. In this regard, there is an increasing interest in thermal methods of production and enhanced oil recovery. The choice of recovery technology and its technological parameters are governed by the effective use of heat, which injected or generated in the formation. It, therefore, depends on the reliability of the initial data on thermal properties, since the thermal conductivity and volumetric heat capacity of the productive formation rocks and host rocks are among the required input data for thermohydrodynamic modeling of the production process. However, reliable information on the thermal properties of rocks is usually lacking, while the typical uncertainty in the thermal properties of rocks is significant (reaches hundreds percent and can lead to errors of tens percent in estimated development indicators). This, along with significant spatial and temporal variations in rock thermal properties, necessitates the conduct of appropriate experimental studies for each development object in order to avoid serious errors that are almost inevitable in opposite cases. The entirety of experimental studies of thermal conductivity, specific and volumetric heat capacity of productive formation rocks and host rocks was carried out for the first time on almost a hundred full-size and standard core samples of three wells drilled in Mayorovskoye and Maryinskoye high-viscosity oil fields of the Samara region. The use of an advanced experimental and methodological base made it possible to obtain information on the thermal properties of rocks of formations A3 and B1 that is unique in volume and degree of reliability.