Batchwise rectification is one of the most commonly used thermal separation operation in the production of fine chemicals and pharmaceiticals, where small amounts of mixtures containing several product or auxiliary components are generally separated. Greater plant flexibility with regard to mixture composition, throughput, and separation specification often also favours batchwise over continuous processing. This publication discusses process engineering possibilities of batchwise rectification of azetropic mixtures with the aid of various examples. It gives a detailed presentation of two industrial batch rectifications with additional feed of auxiliary substances, viz, azeotropic rectification with entrainment agent and extractive rectification. In both cases the set god is to minimise charge times and to maximise the quantities processed in plant operation, with time-optimised control of auxiliary substance throughput being of critical importance in both cases.