This Phase I research will result in a prototype high temperature pressure sensing cell based on the piezoresistive properties of platinum:tungsten alloys. The Eltron Research & Development sensor will be based on a flexible, circular nickel-alloy diaphragm onto which the sensor electrodes will be deposited via sputter coating. A series of insulating and conducting thin-films will comprise the pressure sensing element and an inert protective top-coat will protect the underlying materials from oxidizing/reducing environments and potential degradation from space weather. The prototype sensor will make exclusive use of high-temperature materials in order to facilitate continuous operation in the 5501200 deg. C range (significantly higher than currently available commercial pressure sensors). A technology readiness level (TRL) of 4 will be achieved by the conclusion of Phase I. Phase II research will package the prototype cell into appropriate hardware with all of the necessary on-board electronics for full transducer operation and proceed towards TRL 8.