NdMnO3 exhibits A-type antiferromagnetism with TN =73 K. At 15 K, Nd sublattice orders with a (0, -Fy, 0) type ferromagnetic arrangement. Mn spin reorientation from (Ax, Fy, 0) to (Ax, -Fy, 0) occurs at 15K, and it leads to a reversal of net magnetization. We aim to understand the roles of anisotropy and exchange interactions between Nd and Mn sublattices in magnetization reversal in NdMnO3 by carrying out INS study. The calculated magnetic excitation spectra (based on linear spin-wave theory) will be compared with experimental INS data using the Merlin spectrometer with Ei = 40 meV over 100 – 5 K. The proposed study would reveal the spin Hamiltonian for NdMnO3. The work will be useful to develop a theory to understand the technologically-important phenomenon of magnetization reversal, and would also encourage future INS study on other magnetic materials that show magnetization reversal.