Intensification of production of aldehydes by an exothermic catalysed reaction of propylen and synthese gas (so called hydroformylation) due to higher flow rates of propylene led to unstable operation of reactor. The problem of stabilisation had to be solved, i.e. the reasons for instabilities had to be found and then the method of control of transition to the higher stabilised production had to be proposed. Information obtained by the experimental methods of stimulus-response directly on the industrial unit (record of responses of concentrations of the radiotracer and of the temperatures of the cooling media in the reactor) were used in mathematical modelling of the reactor dynamics. The knowledge accumulated by simulation of the process by proposed physico-chemical model enabled control of operation of the reactor at transition to the higher requires output.