The feasibility of detection of delaminations in thermal composite structures using piezoelectric layers or patches embedded within or bonded on the laminate is investigated. Characteristic damage signatures are sought, associated with changes in the voltage output of the sensors as a result of thermally-induced strains in the laminate. Analytical solutions are developed within the limits of linear thermopiezoelasticity and laminate theory and the resultant voltage across the piezoelectric sensors is calculated. Numerical examples are presented for cantilever beams subjected to temperature variations and the feasibility of the proposed method is illustrated.