This work presents a prediction-based scheme to control a class of unstable delayed (bio)-chemical processes. The main characteristic of the control scheme is that it is based on a predicted future state that is estimated using a prediction-observation protocol that allows compensating large time-delays. The convergence of the prediction error is shown through standard stability arguments. The stability of the closed-loop system is shown by invoking the separation principle between the prediction error and the control based on estimated variables feedback. Four numerical examples are used to illustrate our results, including two time-delayed benchmark case studies taken from the control process literature. (C) 2020 Elsevier Ltd. All rights reserved.