Power consumption in large disposable shaking bioreactors can be readily measured by monitoring the temperature change of a fluid over time until steady state. However, as viscosity changes with temperature and power consumption depends on viscosity, no defined conditions exist. Therefore, an extended temperature method for determination of power consumption in disposable large shaking bioreactors of size >2 L is introduced and compared with the conventional temperature method. Dynamic simultaneous parameter estimation using several different data sets is performed for evaluation of model parameters. Results indicate suitability of the new method for measurement of power consumption for fluids possessing water-like viscosity as well as for viscous Newtonian fluids. The maximum values of power consumption obtained for water and for an 80% glycerol/water system is approximately 10 kW/m(3) and 23 kW/m(3), respectively. A non dimensional description of power consumption is given. The unusual behaviour observed in the value of power consumption in the 50 1, vessel reveals that, under specific conditions, obviously "out-of-phase" conditions are encountered, necessitating further investigation at different shaking diameters.