With the much improved design and processing technology realised in recent years, GTO manufacturers have been able to offer improved device performance particularly relating to reduced snubber requirements. This has enabled system engineers to reduce the overall losses but at the expense of increased power dissipation within the device. This aspect, combined with the trend toward air-cooled systems which are much less efficient than an equivalent freon or oil-based heat exchanger, has pushed the device manufacturers to further reduce their device losses so that the junction temperature is maintained below the current maximum limit of 125-degrees-C. This article discusses the important trade-offs in GTO electrical parameters with device design features, and details the associated merits and demerits of each. Particular emphasis is placed on the device losses.