The investigation of heat exchanger dynamics has been carried out. The three kinds of exchangers have been taken into consideration: the low power plate heat exchanger, the high power industrial heat exchanger and the model of heat exchanger. The dynamics of the examined exchangers has been analyzed using the parametric identification methods and their implementation in MATLAB. The character of observed phenomenon is not unique. In some of the cases it shows inertial character, in the others oscillatory character. It might indicate an appearing of the kind of a thermal oscillation during the non-stationary states of the heat exchanger. (C) 2012 Elsevier Ltd. All rights reserved.