The stress generated due to the temperature difference is called thermal stress. Generally, the temperature gradients, thermal shocks, and thermal expansion or contraction are most effective contributors to thermal stress. The improper temperature profile of a body results in the formation of cracks, fractures, or plastic deformations at single or multiple spots depending upon two factors (i.e., the magnitude of temperature distribution or other variables of heating and material properties). So, this chapter analyses the causes of thermal stress and their measurement techniques. However, as most of the engineering problems, the thermal stress is due to the thermal expansion or sudden temperature changes happening in the body. Therefore, a brief analysis of temperature measurement devices with their proper data capturing methodology is also discussed.