Owing to the need of a detailed description of flow patterns of liquid-solid and liquid-gas-solid fluidized-bed systems, among them the fluidized-bed bioreactors, the heat pulse anemometry as a time of flow measuring technique of local mixing behaviour of fluids was introduced. The theoretical base, and the experimental conditions of the application, e.g. the effects of the measuring parameters as heating voltage, sweeping time and measuring time were explained. The fluidized bed bioreactor which has been built to perform the HPA measurements and the experimental set was shown in details. An example for the evaluation procedure was set.