Electrical discharge machining (EDM) is a non-conventional machining process in which material removal is accomplished through spark erosion between a workpiece and tool electrode. Process stability is of great importance to the productivity of the EDM process, especially in the wire EDM configuration where an unstable process could lead to wire breakage having a detrimental effect on productivity. This thesis investigates the application of acoustic emission (AE) in EDM as a process monitoring technique. AE techniques have been applied to almost all machining processes; however its benefit as applied to EDM has not been investigated yet. The AE signal from the EDM process is related to various EDM parameters including, electrical parameters, tool materials, flushing and some process modifications, such as dispersing metallic powder into the gap. Using this knowledge, the benefits of using an AE sensor for a real-time process monitoring technique have been proven.