The inelastic neutron scattering spectra were measured for several Sr concentrations of polycrystallineLa2−xSrxNiO4.We find that the generalized phonon density-of-states is identical forx=0andx=1/8.Forx=1/3andx=1/2,the band of phonons corresponding to the in-plane oxygen vibrations (>65 meV) splits into two subbands centered at 75 meV and 85 meV. The lower frequency band increases in amplitude for thex=1/2sample, indicating that it is directly related to the hole concentration. These changes are associated with the coupling of oxygen vibrations to doped holes which reside in theNiO2planes and are a signature of strong electron-lattice coupling. Comparison ofLa1.9Sr0.1CuO4andLa1.875Sr0.125NiO4demonstrates that much stronger electron-lattice coupling occurs for particular modes in the cuprate for modest doping and is likely related to the metallic nature of the cuprate. ©1999 American Institute of Physics.