This thesis illustrates a method for identifying the traits of a multi-enzymatic reaction and defining potential problems early. A systematic approach has been followed and xylulose 5-phosphate synthesis was used as an example. On a commercial level xylulose 5-phosphate is chemically difficult to produce and therefore biocatalysis has been considered as an alternative. A characterisation procedure was developed for this system involving triosephosphate isomerase and transketolase. Particular attention was given to the mechanics of running the system starting from dihydroxyacetone phosphate and glyceraldehyde 3-phosphate rather than fructose 1,6 bisphosphate. The results were used to indicate the process limits for this model system and the supply of glyceraldehyde 3- phosphate was shown to be the key bottleneck in the production. These data were reported in the form of operating maps / windows for the process. The scientific information gathered on the multi-enzymatic system together with key engineering concepts were used to synthesise alternative process routes for the production of xylulose 5-phosphate. These processes were screened based on their attributes and a logical scoring process was developed. This scoring considered the economics, thermodynamics, kinetics and the complexity of each process for the selection and operation of the most scalable option. As a result, unattractive or unviable biocatalytic systems were eliminated early. The best process options for production were identified and tested. These process selection techniques would appear to be applicable to a broad range of biocatalytic systems and could prove vital in ensuring industrial success at an early stage of process development.