Summary: This paper is concerned with the well-posedness and stability of a one-dimensional thermoelastic truncated Timoshenko system of Type III. In order to establish the well-posedness, we first solve an auxiliary problem and give the proof in details, using the semigroup theory and some non traditional operators. Then, we use this result to solve our original problem. After that, we prove that the presence of the thermal effect in one equation only is strong enough to drive the system exponentially to rest, irrespective to any relation between the coefficients. By the end of the work, we present some numerical tests to illustrate our theoretical findings.