Rotary dryers are commonly used to dry particulate in a range of food and mineral processing industries. The purpose of this work was to study the design and performance of a rotary dryer. It was evaluated the number of flights and operational conditions that corresponding to the optimal performance for the equipment. A set of equations to predict the solids holdup in flights with three and two segments was also evaluated. Their predictions were compared to measurements performed with a pilot plant rotary dryer. The equation generated very accurate estimations.