Recently, it has been reported that CeFeAsO belongs to the orthorhombic structure where both Fe and Ce orders antiferromagnetically around 140K and 4K, respectively, whereas Ce ions in CeFePO, possessing tetragonal structure, are in paramagnetic heavy fermion state that lies close to the ferromagnetic instability. Investigations of CeFeAs1-xPxO system reveal a switching from an antiferromagnetic to a ferromagnetic Ce-state at x=0.4, due to a stronger hybridization between the 4f-states of Ce and the 3d-states of Fe near the EF connected with the inherent valence instability of Ce. We, therefore, propose to carry out inelastic neutron scattering investigation on polycrystalline CeFeAs1-xPxO (x ~ 0, 0.04, 0.2, 0.37, 0.7, 0.92, 1.0) compounds to understand the crossover between AFM-Kondo lattice and Spin density wave type of interaction as a function of the composition and temperature.