In this work a hybrid neural modelling methodology, which combines mass bal
ance equations with functional link networks (FLNs), used to represent kine
tic rates, is developed for bioprocesses. The simple structure of the FLNs
allows the easy and rapid estimation of network weights and, consequently,
the use of the hybrid model in an adaptive form. As the proposed model is a
ble to adjust to kinetic and environmental changes, it is suitable for use
in the development of optimization strategies for fed-batch bioreactors. Th
e proposed methodology is used to model the processes for penicillin and et
hanol production, and the development of an adaptive optimal control scheme
is discussed using ethanol fermentation as an example.