A new method has been developed which allows determination of the coagulation coefficient of two oppositely charged particles experimentally. For this purpose, quasi-monodisperse particles of different sizes and morphology were used to study the influence of different parameters on the coagulation coefficient. A good agreement between experimental results and the classic Fuchs' theory was obtained when including a method accounting for particle nonsphericity. In experiments with polydisperse bipolarly charged aerosols, no principal differences to uncharged aerosols were found when a dimensionless representation was used. Changes in particle number concentration and geometric mean diameter can be described by simple empirical expressions.