Extreme Devices has fabricated and tested gated CVD diamond microtip arrays for use as cold cathodes in a variety of high power, high temperature, and high radiation applications. The uses for these devices include direct replacement of hot filament cathodes, microwave amplifiers, spaceborne sensors, and other areas requiring devices that provide high current output and that will function in harsh environments. The basic architecture of the device including an overview of the method for obtaining the self-aligned gated diamond microtip array is presented. Key developments for these robust devices include low electron extraction fields (3 V/μm), high current density output (>75A/cm2), stable operation for long periods of time, and operation in severe (high pressure) conditions. The gated cathodes offer low turn-on voltages (22 V) and appear to be well suited to a number of applications.