Research into surface acoustic wave (SAW) devices began in the early 1970s and led to the development of high performance, small size and high reproducability devices. Much research has now been done on the application of such devicesto consumer electronics, process monitoring and communicatrion systems. The use of novel materials such as gallium phosphate (GaPO4), extends the operating temperature of the elements. SAWevices based on this material operating at 434 MHz up to 800C, can be used for passive wireless sensor applications. Interdigital transducer (IDT) devices with Platinum/ Zirconium metallization and 1.4 micron finger-gap ratio of 1:1 have been fabricated using direct-write e-beam lithography and a lift-off process. The performance and long term stability of these devices has been studied, and the results are reported in this paper.