Rietveld refinement of neutron and x-ray diffraction data of Na0.5Bi0.5TiO3 shows R3c phase stabilization at room temperature. The intermediate antiferroelectric region between 180°C to 280°C exhibits phase coexistence i.e R3c + Pnma, along with decrease in octahedral tilt angle and increase in unit cell volume. The local structural changes observed from Raman scattering in the A-O, Ti-O and TiO6 phonon modes favor the global structural variation. A possible antiparallel cation displacement due to Pnma phase formation leads to the origin of antiferroelectric ordering in Na0.5Bi0.5TiO3. © 2015 AIP Publishing LLC.