The influence of composition on the structural ordering and magnetism in the V Nb S system has been investigated by X-ray diffraction and magnetic measurements. Stoichiometric V NbS did not exhibit the structural ordering of vanadium between the NbS layers. In the ordered structure, the vanadium composition deviated from the ideal value of x = frac(1, 3) to both higher and lower values, while the niobium composition was in the range of 0.05≤y≤0.18. Excess niobium, y>0, is thought to play an essential role in the structural ordering in this system. For samples with excess niobium and ordered structures, a magnetic transition was observed at 20-50 K, depending on the composition. The spontaneous magnetization of 3-5×10 μ /V atom is thought to be intrinsic to this system. The magnetization curves consisted of a constant and a proportional parts of the magnetic field, which correspond to the spontaneous magnetization and high-field susceptibility, respectively. The magnetization curves and the temperature dependencies of the high-field susceptibility were quite similar to those of the canted antiferromagnetic NiS . A correlation between the structural and magnetic ordering is suggested. © 2007 Elsevier Ltd. All rights reserved. x 1+y 2 1/3 2 2 B 2 -3