Pb(Zr,Ti)O-3-Pb(Mn1/3Nb2/3)O-3 (PZT-PMnN) system has been studied for high-power piezoelectric applications. This study investigates this system to find out the composition with high-power density piezoelectric characteristics and low temperature coefficient of resonance frequency (TCF). It was found that the composition 0.9PZT-0.1PMnN (Zr/Ti = 0.51/0.49) modified with 6 mol% Sr exhibits a TCF of -8 ppm/degreesC (-20 to +80degreesC). Further, the dielectric and piezoelectric properties of this composition are as follows: k(P) = 0.53; Q(m) = 800; d(33) = 274; epsilon(33)/epsilon(0) = 1290 and tan delta = 1.1%, which shows the suitability of this composition for ultrasonic devices used under fluctuating thermal environment.