A continuous rotating annular chromatograph was developed for preparative separation of nickel and molybdenum. Dowex 50W-8X cation resin (hydrogen form) was packed in a 505-mm long and 10-mm wide stationary annular column. The feed solution was continuously introduced at the top of the bed by a rotating feed nozzle and was carried down through the annular column with an eluent of 10% sulfuric acid. The products were collected by a rotational tray rotating at the same speed as the feed nozzle. To evaluate the performance of this device, the effect of feed flow mte and rotational speed of feed nozzle were measured. Experimental results were compared with results calculated using model-plate theory. It was found that the optimum feed flow rate, at a constant eluent flow rate of 48.8 mL/min and a rotational speed of 4.5 degree/min, was 3.5 mL/min.