A new oscillating cup viscometer for temperatures up to 2,300°C has been constructed. A vacuum furnace with a graphite heater is used for heating the sample. The temperatures of the furnace and sample are measured by both a thermocouple and a pyrometer. The temperature is controlled with a stability better than 1 K. The oscillation of the cup is measured with a reflected laser beam using a position sensitive detector. The measured values of angle and time are then fitted to an analytical oscillation function. From the parameters of this function, the viscosity values are calculated using the Roscoe formalism. Measurements were carried out on pure metals at temperatures up to 1,700°C because of limitations of the thermocouple. The obtained viscosity values showed good agreement with literature data.