Minimising the environmental impact of a process is an important objective for plant design engineers. It is a goal, however, which is closely linked to the flowsheet structure and, therefore, must be considered at the conceptual stage of the design process. At the same time economic criteria are important for the selection of good designs. Frequently, these goals may result in conflicting designs and compromises are required. In this paper, we describe a multiobjective process synthesis methodology, for the early stages of design, suitable for identifying processes with minimal environmental impact and the desired economic performance. The algorithm is particularly suitable for synthesising bioprocesses and has been implemented in the Jacaranda system, which has been enhanced to consider multiple simultaneous criteria. The synthesis algorithm is demonstrated and evaluated by applying it to the synthesis of a penicillin manufacturing process. The procedure is able to identify a set of flowsheets which satisfy both environmental and economic objectives demonstrating that a multicriteria synthesis tool can be invaluable for design with multiple objectives.