Zirconium phosphate (ZrP) was investigated as a possible proton conductor material in direct hydrocarbon polymer electrolyte membrane (PEM) fuel cells that operate at greater temperatures than conventional PEM fuel cells. Amorphous zirconium phosphate was synthesized in this work by precipitation at room temperature via reaction of ZrOCl2 with H3PO4 aqueous solutions. The conductivity of the synthesized ZrP materials were 7.04 x 10(-5) S cm(-1) for ZrP oven dried in laboratory air at 70 degrees C and 3.57 x 10(-4) S cm(-1) for ZrP powder dried first at 70 degrees C in laboratory air and then processed at 200 degrees C with continuous H2O injection at an H2O/N-2 molar ratio of 6. This work showed that by maintaining appropriate water content in the vapour phase at processing conditions, it was possible to alter the composition of zirconium phosphate to a sufficiently hydrated state, and thereby avoid the normal decrease in conductivity with increasing temperature. (C) 2009 Elsevier B.V. All rights reserved.