This work revealed that the solid solution compounds of Sr2−xBaxNb2O7 are promising lead-free materials for high-temperature piezoelectric sensor application. These compounds were confirmed as ferroelectric materials with high Curie points (> 900°C) by their piezoelectric activity after poling, ferroelectric domain switching in their P–E hysteresis loops and thermal depoling behavior. The effect of Ba substitution on the structure and properties of Sr2−xBaxNb2O7 (x < 1.0) was investigated. The solid solution limit of Sr2−xBaxNb2O7 was determined by XRD as x < 0.6. The a-, b-, c- axes, and cell volume increase with Ba addition. The textured ceramics of Sr2−xBaxNb2O7 were prepared for the first time. The highest d33 was measured as 3.6 ± 0.1 pC/N for Sr1.8Ba0.2Nb2O7.