In the field of high‐frequency acoustic arrays for high‐resolution sonars, some transducers are driven with very high‐power density and long pulse length. This produces a temperature rise in the transducer, leading to the variation of the materials characteristics. This phenomenon may reach the mechanical breaking point. To study this problem, we have developed a tridimensional piezoelectric finite element computer program which takes into account radiation (Helmholtz integral equation) and losses (mechanical, dielectric, piezoelectric). After an acoustic computation, using modal analysis, heat sources due to losses are determined in all the volume of the transducer. A finite element program computes the transient evolution of the temperature. According to the obtained temperatures, materials coefficients are updated and a new acoustic calculation is performed. The process is repeated until maximum dynamic stresses or maximum temperature is reached. Several examples are discussed including transducers with and without matching layer. [Work supported by DRET, France.]