Particulate microelectrophoresis is a technique often employed to determine the electrophoretic mobility or zeta potential of particles in suspensions. Many first (based on microscopic, manual timing of the velocity of individual particles) and second (based on microscopic observation and counterbalanced movement control of an entire field of particles) generation instruments like the PenKem Lazer Zee, model 501, are still in use, although more modern (third generation) machines exist, which not only measure operator-independently the average zeta potential of particles in a suspension, but also their relative proportions in case of heterogeneous suspensions. In this paper, we present a method based on automated image analysis, with which these first and second generation instruments can be upgraded to match the performance of the most modern machines. To this end, the instruments must be extended with a video camera, a computer, a video framegrabber, and accompanying software. Subsequently, images of the particle movements under the influence of the applied voltage are analyzed by so-called angular distribution functions to reveal the distinct particle velocities in a suspension. Comparison of the results of the automated program with those obtained by an experienced operator in the standard mode of a PenKem Lazer Zee, model 501, showed excellent correspondence, whereas further simulations with heterogeneous suspensions demonstrated that the program can adequately calculate fractions of particles of different zeta potentials in a heterogeneous suspension. Finally, three examples are given of automated measurements on homogeneous and heterogeneous bacterial suspensions, demonstrating that the method described indeed provides a means to upgrade the performance of first and second generation instruments to that of the most modern machines.