We report high pressure powder neutron diffraction study in technologically important material sodium niobate using high-flux D20 neutron diffractometer at Institut Laue- Langevin, France. The measurements were carried out using Paris-Edinburgh cell upto 11 GPa in the pressure intervals of 1-2 GPa at 300 K. Rietveld refinement of the powder diffraction data revealed that diffraction patterns could be indexed using the orthorhombic structure (space group Pbcm) up to 6 GPa. Careful inspection of pressure dependence of diffraction data showed appearance and disappearance of certain superlattice reflections around 7 GPa. The new superlattice reflections that appear at 7 GPa, could be indexed by using an orthorhombic phase with space group Pbnm. We also observed that the response of the structural parameters with pressure is strongly anisotropic.