The effects of rotation and secondary flows on flow in rotating, radial-flow passages are investigated. Pressure and hot-wire measurements are made on the developing flow in a single, rotating radial-outflow channel of simple geometry. The channel has straight radial walls, and is of constant height. It is double shrouded, has a total angle of 15 deg, and an area ratio of 3.1:1. The results indicate the formation of a large wake region on the suction (trailing) side of the passage, at high flow rates. At low flow rates, a pressure-side eddy was observed.