A convenient and rapid method for determining diffusion coefficients has been developed that is based on the quasi‐stationary diaphragm cell method. A silver filter membrane is used to separate two compartments of the apparatus that are stirred magnetically with synchronous motors. The advantages are the good precision of the data, running times of the experiments, and the extended repeated usability of a given membrane. Copyright © 1968 Wiley‐Liss, Inc., A Wiley Company