An electric field applied to the CaWO4/V2O5, CaMoO4/V2O5 and CaMoO4/WO3 systems causes grain boundary and surface transports of oxides having a low surface energy (V2O5 and WO3) and their segregation on the grain surface. It was found that V2O5 penetrates to the inner surface of CaWO4 much more intensively when the V2O5 briquette bears a negative potential: (-)V2O5|CaWO4(+). The penetration of V2O5 and WO3 to the inner surface of the CaMoO4 ceramic is accompanied by a chemical interaction. © 2002 Elsevier Science B.V. All rights reserved.