The method of study and experimental researches of the error of method of the thermocouple with controlled profile of temperature field along the main thermocouple are considered in this paper. Experimentally determined values of error of method are compared to the theoretical estimations done using Newton's law of cooling. They converge well.Keywords: Thermocouple, inhomogeneity of thermocouple, controlled profile of temperature field, measurement error, error of method.