Microfiltration (MF) membranes were previously made of kaolin using electrophoresis. In this study, effects of calcination time and temperature on flux and porosity of microfiltration membranes produced by extrusion were evaluated. To complete mullite phase formation, alpha-alumina was added to the kaolin. Sodium carbonate was also used to increase porosity and flux of the membranes. Many experiments should be carried out to understand effects of different parameters. Logical selection of the experiments can save time and money. To obtain the minimum number of experiments with meaningful results, Taguchi's method was used. The MF membranes were successfully made of 30% alumina, 3% sodium carbonate and 67% kaolin. The dried MF membranes were calcined at a temperature of 1100 degrees C. These membranes were characterized using XRD and SEM analysis. The results showed that mullite is major phase of the membranes and maximum pore size of the membranes is 5.5 pm as measured by SEM. Water flux and porosity of these membranes were evaluated as 21.5 kg/m(2) h and 33.92%, respectively.