The crystal structure of a copper antimonite (CuSb2O4) was determined from X-ray powder diffraction data. The structure was solved by simulated annealing in direct space using the Rietveld method. The compound crystallizes in tetragonal symmetry and space group P4 2 bc (106); unit cell parameters a = b = 8.76033(5) Å, c = 5.79786(4) Å, Z = 4, V = 444.947(5) Å3 and density (calc.) = 5.539 g cm−3. The CuO6 polyhedra are strongly elongated due to Jahn–Teller distortion in a [2+2+2] coordination arrangement, i.e. there are two long axial Cu–O1 bonds of 2.447(13) Å and in the equatorial plane there are two intermediate Cu–O2 bonds of 2.07(3) Å and two short Cu–O2 bonds of 1.88(2) Å. The SbO3 pyramidal arrangement is almost regular with Sb–O1 bonds of 1.97(2) Å (2×) and Sb–O2 of 1.959(5) Å. The experimentally obtained Raman spectrum is consistent with values obtained from theoretical modelling studies. The magnetic behaviour of this new compound suggests that it belongs to the class of S = 1/2 Heisenberg chain systems.