By use of potentiometric and spectrophotometric techniques, the complexation of tungsten(VI) with nitrilotriacetic acid (NTA) has been carried out in aqueous solution for pH = 7.5 at 25degreesC and different ionic strengths ranging from (0.1 to 1.0) mol dm(-3) (NaClO(4)). The composition of the complex was determined by the continuous variations method. It was shown that tungsten(VI) forms a mononuclear complex with NTA of the type (WO(3)L(3-)) at pH = 7.5. The dependence of the protonation of the aforementioned ligand and the stability constant of the complex on ionic strength is described by a Debye-Huckel-type equation. Finally the results have been compared with the previously reported data.