Sc-doped barium titanate (BaTiO3) nanopowders and ceramics were prepared by a sol-gel method for the first time. The polymorphism, microstructure and dielectric properties were investigated. Pseudo-cubic Sc-doped BaTiO3 nanopowders with a particle size of 30-40 nm have been achieved at low temperature of 800 degrees C. A phase diagram for the solid solution system BaTi1-xScxO3-delta was obtained. The limit of pseudo-cubic Sc-doped BaTiO3 solid solution (BTss) and the stable hexagonal phase have a large dependence on temperatures. The dopant of Sc3+ can also dramatically refine the grain size of BaTiO3 to 300 nm when x = 0.10. For different Sc3+ content in BaTiO3 ceramics, two types of impedance response appeared, and the resistivity of ceramics was dominated by bulk resistance or grain boundary resistance. Curie temperature (T-C) and dielectric constant decreased by increasing the Sc3+ content. Relaxor behaviour occurs below room temperature when x = 0.10. (C) 2013 Elsevier Ltd. All rights reserved.