Control systems are of great technological, scientific, and economic importance. Their applications are in the most diverse areas such as telecommunications, transportation, navigation, medicine, biology, astronomy, space and air travel, and much more. This paper presents an application of system identification using Smith's Method for thermal systems. An Arduino board communicating with Matlab software is used for this. The actual temperature curves are presented as well as the estimated curves, therefore the transfer functions are presented as the final result of the work.