and 20,000 psi (137.9 MPa), whereas high temperature instrumentation falls into three categories: Hostile Environment [H.E.; 3500-4000F (1770-2040C), 20,000 psi (137.9 MPa)] Ultra Hostile Environment [U.H.E.; 4000-5000F (2040-2600C), 25,000 8si (172.4 MPa)] Geothermal Environment [G.E.; 500 F+ (2600C+), 15,000 psi (103.4 MPa)] Instrument specifications and associated wireline operational technology required for logging hostile environments will be discussed. Field case examples are presented.