This paper presents measurements and predictions of the pressure-loss coefficient for a wide-angle, three-dimensional diffuser with free discharge. The constant tracer-gas method was used for measuring duct mean velocity, and static pressure tappings for pressure change across the diffuser. The effect on the loss coefficient of a bend preceding the diffuser was investigated for various spacer lengths. Computational fluid dynamics predictions were carried out to study flow stabilities in diffusers of different divergence angles.