Abstract: The speed of sound in a fluid is determined by, andtherefore an indicator of, the thermodynamic properties of thatfluid. The aim of this study was to investigate the use of anultrasonic cell to determine crude oil properties, in particular oildensity. An ultrasonic cell was constructed to measure the speedof sound and tested in a crude oil sample. The speed of soundwas measured at temperatures between 260 and 411 K at pressures up to 75 MPs. The measurements were shown to lead to an accurate determination of the bubble point of the oil. This indicates that there is a possibility of obtaining fluid density from sound speed measurements and suggests that it is possible to measure sound absorption with an ultrasonic cell to determine oil viscosity.