We report on the determination of the electro-neutron-optic coefficient of sup>7LiNbO3:Fe. Standard hologram recording results in a space-charge field that generates a spatially varying strain field via the inverse piezoelectric effect. This is regarded as a neutron refractive-index change from which cold neutrons are diffracted. A measurement of the angular dependence of the neutron diffraction efficiency enables us to calculate the first electro-neutron-optic coefficient.