ABSTRACT Diamond appears to have many attractive properties for the fabrication of high power, high frequency, high temperature semiconducting devices, and many theoretical calculations suggest that the power-handling and frequency response of a diamond device would surpass those of devices made from silicon or GaAs. However, diamond suffers from a number of problems which severely limit its prospects in device applications. Semiconducting single-crystal diamond may only be produced as p type, and even here it is extremely difficult to grow material of device quality. Furthermore, we show that errors in the literature have led to an over-optimistic picture regarding the improvements in performance that may, in principle, be achieved by using diamond devices. We conclude that the likelihood of such devices outperforming silicon or GaAs seems extremely remote.