A high-gravity vapor-liquid contactor ("Higee") was studied under distillation conditions using a semiworks scale system. The cyclohexane/n-heptane test mixture was used at operating pressures of 166 and 414 kPa and under total reflux conditions. Rotational speeds ranged from 400 to 1200 rpm. Data were collected on mass transfer efficiency, pressure drop, and hydraulic capacity. As many as six transfer units were achieved in a bed depth of 21 cm, with efficiency being directly proportional to speed of rotation. Models were developed for mass transfer and pressure drop, and the earlier packed bed flooding model of Sherwood, which includes a gravity term, was found to represent the vapor capacity of the contactor. Sufficient information is given to enable the preliminary design of a system containing a high-gravity vapor-liquid contactor. Because the test mixture has been widely used for conventional contactor studies, means for comparing high-gravity contacting with other methods are now available.