The properties of solid solution La2Mo2-xWxO9 (x = 0.8, 1.0, 1.2, and 1.4) prepared by microwave synthesis are investigated. Open circuit voltages (OCV) as a function of temperature for pure and W-doped samples are reported and these data suggest that La2Mo0.6W1.4O9 performs best in the temperature range 550-650 degrees C. where the stability of the sample under operating conditions appears to be good and the OCV values close to 1 V. Electrochemical measurements for an electrolyte-based cell were taken over the temperature range 550-650 degrees C and found to be, as expected, strongly dependent on the electrolyte thickness. These results support the claim that W-doped Lamox can be used as an electrolyte material at temperatures close to 650 degrees C; with a suitable choice of electrode materials and a change in the fuel cell geometry from electrolytesupported to electrode-supported so that the electrolyte thickness can be reduced considerably, Lamoxbased fuel cells are expected to produce useful power densities. (C) 2010 Elsevier B.V. All rights reserved.