In this paper the first experiment of thermomagnetic writing of a hologram on a thin film of EuO and the reconstruction of the hologram is reported. Writing of the hologram is achieved by using a giant pulsed ruby laser as a source for thermomagnetization. Erasing of the hologram is accomplished by a small applied magnetic field. The ruby laser is used because of its ability to provide the energy required for writing in a time that is short compared with the thermo-relaxation time. A hologram with shallow angle (10 μ resolution) was recorded and the reconstruction of the hologram was done using a HeSingle Bond signNe laser as a source. The formation of the hologram is based on the fact that the index of refraction of the material is a function of magnetization. Thus, the different state of magnetization induced by the laser pulse acts as a phase-hologram for polarized light. Polarizing elements were used to observe the reconstructed images from the magnetic holograms. Results were also obtained for the diffraction intensity in the different orders of a simple thermo-magnetic hologram. An analysis is presented to interpret the observed phenomena and gives the calculated efficiency that can be obtained under ideal conditions. © 1969 The American Institute of Physics.