Crystals of the title compound, (C16H36N)(4)[(p-NC-C6H4As)(4)Mo12O46] or (C16H36N)(4)[{As(C7H4N)}(4)Mo12O46], were synthesized by the reaction of p-cyanophenylarsonic acid and sodium molybdate at low pH. With nitrile groups pointed in tetrahedral directions, these new organically modified polyoxometalate clusters are potential building blocks in coordination networks.