It forms light green hexagonal crystals.

[2] Praseodymium(III) oxide can be used as a dielectric in combination with silicon.

[2] Praseodymium-doped glass, called didymium glass, turns yellow and is used in welding goggles because it blocks infrared radiation.

Praseodymium(III) oxide is also used to color glass and ceramics yellow.

[3] For coloring ceramics, also the very dark brown mixed-valence compound praseodymium(III,IV) oxide, Pr6O11, is used.