  A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <=
x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal
CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm;
a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon
chemical doping with Na, the CDW/SDW transition is systematically suppressed
and super-conductivity arises with the critical temperatures, Tc, increasing to
5.5 K. Bulk superconductivity is confirmed by resistivity, magnetic and heat
capacity measurements. Like the high-Tc cuprates and the iron pnictides,
superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and
differences to the cuprate and iron pnictide supercon-ductors are discussed.
