Single crystals of BaV 13 O 18 (V +2.62 ) containing a small amount of Cr (about 7% of vanadium sites) were prepared by heating a mixture of BaCO 3 , V 2 O 5 , V, and Cr powders at 1973 K for 40 h in flowing Ar. Crystal structure analysis using single-crystal data (Rigaku AFC7R, 4037 reflections) showed that the BaV 13 O 18 has a rhombohedral unit cell with a h =12.621(5) Å, c h =7.020(5) Å, V=968.4(9) Å 3 , Z=3, D cal =5.595 g·cm −3 , and space group R−3 (R 1 =1.96%, wR 2 =3.60%, S=1.095). In the structure, Ba and O formed a cubic close-packed arrangement and every V was coordinated by six O. BaV 13 O 18 has three kinds of vanadium environments: one almost regular octahedral site and two distorted octahedral sites. VO 6 octahedra share their corners and edges.