A review. Rational and efficient process development in chem. technol. always makes heavy use of process anal. in terms of balances, kinetics, and thermodn. While the first two of these concepts have been extensively used in biotechnol., it appears that thermodn. has received relatively little attention from biotechnologists. This state of affairs is one among several reasons why development and design of biotechnol. processes is today mostly carried out in an essentially empirical fashion and why bioprocesses are often not as thoroughly optimized as many chem. processes. Since quite a large body of knowledge in the area of biothermodn. already existed in the early nineties, the Steering Committee of a European Science Foundation program on Process Integration in Biochem. Engineering identified a need to stimulate a more systematic use of thermodn. in the area. To this effect, a biannual course for advanced graduate students and researchers was developed. The present contribution uses the course structure to provide an outline of the area and to characterize very briefly the achievements, the challenges, and the research needs in the various sub-topics. [on SciFinder (R)]