The perovskite-like layer structured strontium niobate (Sr(2)Nb(2)O(7)) and calcium niobate (Ca(2)Nb(2)O(7)) are good candidates for high-temperature piezoelectric applications because of their high Curie points. Single-phase dense Sr(2)Nb(2)O(7) and Ca(2)Nb(2)O(7) ceramics with grain-oriented microstructures were prepared by spark plasma sintering using a two-step method. The Lotgering orientation factors were 0.86 and 0.70 for Sr(2)Nb(2)O(7) and Ca(2)Nb(2)O(7), respectively. The T(c) of Sr(2)Nb(2)O(7) and Ca(2)Nb(2)O(7) were measured as 1327 +/- 5 degrees C and above 1525 degrees C, respectively. The dielectric, piezoelectric, ferroelectric properties, and direct-current electrical conductivity are higher along the directions perpendicular to the pressing direction compared with parallel. The piezoelectric constant d(33) for Sr(2)Nb(2)O(7) was 2.8 +/- 0.2 pC/N.