Abstract: A rotating evaporator device is disclosed for the distillation or concentration of liquids. The rotating evaporator device of the present invention utilizes a multiplicity of pairs of disks wherein each disk pair forms a cavity within which heating vapor condenses on the interior surfaces of the disk pair and evaporation occurs from a thin film of distilland deposited on the outside surfaces of the disk pair by means of flexible wipers pressing on the outside surfaces of the disk pair. The centrifugal force created by the rotation of the disks causes the distillate and distilland films to be very thin resulting in very high heat transfer coefficient. The pairs of disks are joined together at the inside peripheries and are rotated about a stationary hollow shaft wherein heating vapor is introduced into the cavities through ports in the shaft and stationary scoops are connected to the shaft to withdraw the condensate from the circumferential peripheries of the cavities.