Abstract— Determination of heat exchange between a solid and the environment is a significant inverse thermal physical problem. This heat exchange law irrespective of its nature can be defined easier if mean temperature of such solid is known. When mean temperature of the solid and speed of its change are known, it becomes possible to determine heat flow on the boundary of the solid. In its turn, when heat flow on the boundary, temperature on the boundary and ambient temperature are defined, heat exchange coefficient can be established. Therefore, the main attention is paid to a manner how mean temperature of a solid can be determined in the article. Examining inverse heat transfer problems, input data consist of measurements taken in temperature field as simple as possible mathematically in laboratory conditions. Hence, a symmetrical one-dimensional temperature field is discussed in the article.