A major bottleneck in developing industrial enzymes is the lack of a method for determining catalyst process stability quickly and efficiently. In order to solve this problem, a new method for the fast in-situ characterisation of activity and long-term stability has been developed. The necessary theory of modelling enzyme activation and deactivation is presented. As a model reaction we have chosen the carboxy-esterhydrolase-catalyzed hydrolysis of triglycerides. These reactions were performed in a fed-batch and continuous flow reactor. To accelerate the process of ageing, the temperature was continuously increased during the experiments. The procedure of parameter determination on the basis of experimental results is described for first-order, series and parallel deactivation mechanisms. Additionally, several criteria for choosing the applicable mechanism are presented. As an application of the new method, the influence of immobilisation on activity and stability of the immobilised enzymes was investigated. The temperature dependency of characteristics such as initial activity, half-life time and turn-over-number were determined.