We have used the Full Potential Nonorthogonal Local-Orbital minimum basis method (FPLO) in the Local Spin Density Approximation (LSDA) to calculate the electronic, magnetic and elastic properties of CeN and PmN. We predicted a phase transition from Rock Salt structure (RS) to Cesium Chloride (CsCl) structure in both CeN and PmN compounds at pressures of 40.7 and 42 GPa respectively. The half-metallic property was found only in the RS phase of PmN. The CeN compound, however, shows a metallic behavior in the two structures. The calculated bulk modulus of CeN and PmN in RS structure are 170.02 GPa and 154.6 GPa respectively. For PmN the energy gap and the total magnetic moment are 0.56 eV and 4 µB respectively.