The development of high-powr ignitrons with peak current ratings of up to 1000 kA and simultaneous charge transfer rates of 250–500 C is currently under way in a joint effort between Texas Tech University (TTU), Lawrence Livermore National Laboratory (LLNL), and industry. Two industrial manufacturers, Richardson Electronics, US, and English Electric Valve, UK, have participated with TTU and LLNL in three workshops to advance the state of the art in high-power ignitrons. Less than three years after the start of the program, the cooperative efforts have led to the development of a new commercial tube (Richardson Electronics NL-9000). High power testing of proto-types of this tube and other unique ignitrons was done by Kihara at LLNL. Research at TTU is concentrated on plasma diagnostics, novel anode designs, electrode placements, and trigger schemes. Electrical measurements as well as optical and microwave plasma studies, such as high-speed framing photography, Mach-Zehnder and microwave interferometry., and spectroscopy have been performed. This paper describes the advances made in high-power ignitron switching capabilities in a comparison study between conventional Size D and Size E tubes, demountable experimental tubes and the new NL-9000 (Richardson Electronics). The paper shows the differences in tube design, and the associated peak current and charge transfer capabilities and lifetime expectancies. The critical design criteria are the anode shape and placement in order to control the plasma and prevent prefires. Tube failure modes and recent studies on alternate ignitor schemes are presented. In addition, results of plasma diagnostics performed on a demountable ignitron with optical access to the discharge plasma are shown. Time resolved images of the interference patterns from an optical Mach-Zehnder interferometer were recorded with a mechanical high-speed camera and evaluated with the help of image processing.