A number of methods were used to study the electrical properties of lanthanide tungstates Ln(2)(WO4)(3) (Ln = La, Sm, Eu, Gd) and the type of charge carriers is determined. The studied compounds have a salt-like isle structure with isolated tetrahedrons, which crystallise in the Eu-2(WO4)(3) structural type of the so-called 'defective scheelite' in which 1/3 of Ln sites are vacant, Ln(2/3)[V-Ln](1/3)WO4. Predominant ionic conductivity in Ln(2)(WO4)(3) (Ln = La, Sm, Eu, Gd) was established both by the EMF method and from independence of conductivity versus oxygen partial pressure, although Eu-2(WO4)(3) reveals a small contribution of the electronic n-type component. A minor contribution (1-5%) of the anion [WO4](2-) transport was detected by the Tubandt method, which along with the results of the EMF technique proves the predominant oxygen conductivity. (C) 2017 Elsevier B.V. All rights reserved.