Bi2Te3 nanowires were grown in a nanostructured Al2O3 matrix by potential-pulsed electrochemical deposition. The wires had diameters of 50 nm to 80 nm and length of about 56 m. Cross-sections prepared for scanning electron microscopy revealed uniform growth with deviations in length of less than 10\%. The wires were deposited with reduction potentials between -150 mV and -250 mV. A reduction potential of -200 mV yielded an average Te content of 63.2 at.\% as determined by calibrated, high-accuracy energy-dispersive x-ray spectrometry in transmission electron microscopy (TEM). The chemical composition was uniform along the length of the nanowires but depended on their diameter. The Te content increased by about 1 at.\% when the diameter of the nanowires decreased from 80 nm to 50 nm. Selected-area electron diffraction combined with dark-field TEM imaging revealed single-crystalline wires; no grain boundaries were detected. The nanowires grew along the {[}110] and {[}210] directions; the axis was perpendicular to the wire axis, allowing basal plane transport unaffected by grain boundaries.