A brief study is described of a simple method for producing plane shock waves in solids at pressures higher than those attainable by conventional explosive methods. Mach reflection of a conically convergent shock in the specimen yields a disk‐shaped front at a pressure of several megabars, depending on the type of explosive employed and the specimen material; this front is accessible to Hugoniot equation‐of‐state measurements. Results for copper at a pressure of 1.9 Mbar are in good agreement with published values.