Submicron-structured (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ (BNBT6) ceramics were obtained from nanometric powder synthesized by sol–gel auto-combustion at 500 °C. Hot-pressing at low temperatures and a combination of this with recrystallization, still moderate in order to reduce the loss of volatile elements, have been tested. Material properties, including all losses, were determined at the resonances of thin discs using Alemany et al software. Ceramics hot-pressed at 700–800 °C for 2 h have a pseudo-cubic structure, a grain size of a few hundred nanometers and are homogeneous. Both their crystal structure and the lack of sintering prevent their poling. For ceramics hot-pressed at 950 °C for 3 h, Bi or Bi_0.5Na_0.5 loss, together with low piezoelectric properties (d₃₃ = 60 pC N ^{− 1}, k_p = 8.3% and k_t = 9.5%), was observed. Recrystallization at 1000 °C-1 h of ceramics hot-pressed at 700 and 800 °C for 2 h keeps the submicron structure, reduces porosity and prevents off-stoichiometry. Mechanical and piezoelectric losses are also reduced and coupling factors increased (k_p = 24.6%, k_t = 36.4%). The best piezoelectric coefficient obtained in these ceramics (d₃₃ = 143 pC N ^{− 1}) is comparable with those reported for coarse-grained ceramics.