Eu4As3 crystallizes in the cubic I-43d space group. The structure is three-dimensional. Eu+2.25+ is bonded to six equivalent As3- atoms to form a mixture of distorted edge, face, and corner-sharing EuAs6 octahedra. The corner-sharing octahedra tilt angles range from 20–48°. There are three shorter (3.03 Å) and three longer (3.34 Å) Eu–As bond lengths. As3- is bonded in a 8-coordinate geometry to eight equivalent Eu+2.25+ atoms.