In high speed grinding research it is required to measure temperature within the workpiece. Present techniques are thermocouple based, and often suffer from excessive electrical noise on the signal. This paper presents a number of novel fiber optic sensing devices that overcome this limitation and also offer greater performance. Optical fiber devices are simpler to place in situ prior to the machining tests and they offer faster response and greater sensitivity than was previously possible. Results are presented from machining tests and the new devices are compared with each other and previous techniques.