Single-phase perovskite-type reduced tantalates, Na 1 ؊ x Sr x TaO 3 with 0 < x40.4, have been synthesized by heating mixtures of NaTaO 3 , Sr 5 Ta 4 O 15 and Ta in sealed tantalum ampules at 14003C for 20+24 h. At Sr contents of 0.54x40.8 and above 14003C, polyphasic samples were obtained. X-ray powder di4raction (XRD) and transmission electron microscopy studies (selected area (SAED) and convergent beam electron di4raction (CBED)) showed an orthorhombic distortion of the x ؍ 0.1 sample (GdFeO 3 type, space group Pnma). The interpretation of the XRD, SAED, and CBED studies indicates the crystallites found in the x ؍ 0.2 and 0.3 samples to consist of domains with tetragonal and orthorhombic symmetry having the unit cell parameters of a ؍ b+(2a per and c+2a per and a+b+(2a per and c+a per (a per cell axis in the ideal perovskite structure), respectively. The x ؍ 0.4 sample was cubic (space group Pm3m) with a ؍ a per . Resistivity measurements showed that all samples are semiconducting and that the conductivity increases with Sr content. Magnetic measurements of Na 0.6 Sr 0.4 TaO 3 revealed a diamagnetic behavior down to 20 K. Below this temperature a slight paramagnetism arises.