The aim of this paper is to present investigations of the influence of geometry of the pendulum agitators with clapping blades and of the physical parameters of mixed fluid on the homogenisation time, the power consumption and the energy of mixing. Measurements were carried out using a vertical cylindrical vessel having a diameter of 0.5 in filled with 0.5 in height of liquid. An agitator was inserted centrally into the mixer and mounted on a rod jointed with a mechanism transforming the rotational movement into the forward-backward movement in the horizontal direction. The mixing power of an agitator was calculated from a measured deforming force acting on a dynamometric ring. The homogenisation time was determined by the thermal method as well as by the concentration method. Based on analysis of the experimental data original formulas were proposed for determination of the mixing power, the homogenisation time and the mixing energy. (C) 2003 Elsevier B.V. All rights reserved.