Resonance methods were used to determine the variation of several piezoelectric, elastic and dielectric constants, as well as the corresponding electromechanical coupling factors of soft and hard doped Pb(ZrxTi1-x)O3 (PZT) ceramics, with compositions near the morphotropic phase boundary (MPB), as a function of temperature ranging from −165 °C to 195 °C. The material constants were obtained by analyzing the fundamental resonance of the impedance or admittance spectra as a function of frequency for several sample resonance geometries. The piezoelectric constants d33 and −d31, as well as the dielectric constants εT33, generally increased with temperature for both soft and hard PZT samples. However, the elastic constants sE11 and -sE12 exhibited abnormal variations seen as broad peaks over parts of the tested temperature range. Furthermore, thermal hystereses were observed in all the studied material constants during the heating and cooling cycles. Finally, it was noted that, overall, the material constants of soft PZT varied significantly more than those of hard PZT under changing temperature conditions.