Spontaneous ignition phenomena have been evaluated for eight experimental hydraulic fluids. The technique of thermo-electric flame detection has been us-J to determine the minimum spontaneous ignition temperature for each system ii air at one atmosphere pressure. Differential thermal analysis has been employed for the study of the thermal and oxidative degradation of two experimental lubricants in the presence of several metal oxide catalysts. Six other lubricant systems without added catalytic agents have been subjected to This document is subject to special export controls and each transmittal to foreign governments or foreign nationals may be made only with prior approval of the Fluid and Lubricant Materials Branch,