The present work includes experimental and theoretical studies of the characterization of filter cakes. A filter test apparatus, in which the local pressure profile can be determined during the build up of the filter cake was developed. Efforts were made to minimize the influence of settling and the so called wall-effects related to the pressure measurements. Also a method to calculate local filtration properties (specific filtration resistance and porosity) was developed. In the method, conventional empirical equations describing the relation between the local filtration properties and the local pressure were used. The basic idea is to direct the calculation in such a way that the obtained numerical values of the parameters in the empirical equations reflects the local conditions. The developed method was found to be superior compared to a method where only average data on the filtration properties was used to calculate the corresponding parameters. Finally, the method was found to be stable as well as reliable.