Europium(II) oxide can be prepared by the reduction of europium(III) oxide with elemental europium at 800 °C and subsequent vacuum distillation at 1150 °C.^[2]

Eu₂O₃ + Eu → 3 EuO

It is also possible to synthesize from the reaction of europium oxychloride and lithium hydride.^[3]

2 EuOCl + 2 LiH → 2 EuO + 2 LiCl + H₂

In modern research, thin films can be manufactured by molecular beam epitaxy directly from europium atoms and oxygen molecules. These films have contamination of Eu³⁺ of less than 1%.^[4][5]

Europium(II) oxide is a violet compound as a bulk crystal and transparent blue in thin film form. It is unstable in humid atmosphere, slowly turning into the yellow europium(II) hydroxide hydrrate and then to white europium(III) hydroxide.^[3] EuO crystallizes in a cubic sodium chloride structure with a lattice parameter a = 0.5144nm. The compound is often non-stoichiometric, containing up to 4% Eu³⁺ and small amounts of elemental europium.^[6] However, since 2008 high purity crystalline EuO films can be created in ultra high vacuum conditions. These films have a crystallite size of about 4 nm.^{[citation needed]}

Europium(II) oxide is ferromagnetic with a Curie Temperature of 69.3 K. With the addition of about 5-7% elemental europium, this increases to 79 K.^[2] It also displays colossal magnetoresistance, with a dramatic increase in conductivity below the Curie temperature. One more way to increase the Curie temperature is doping with gadolinium, holmium, or lanthanum.^[6]

Europium(II) oxide is a semiconductor with a band gap of 1.12 eV.^[6]

Because of the properties of europium(II) oxide, thin layers of the oxide deposited on silicon are being studied for use as spin filters. Spin filter materials only allow electrons of a certain spin to pass, blocking electrons of the opposite spin.^[7]