The results of tests performed on the drying of unfired tiles by the action of microwaves are presented. These results show that a reduction of more than 5% humidity can be achieved in less than 5 minutes in a well designed system. Some aspects concerning the difficulties met at the static tests are also given. Some effects of the changing properties of the tiles during the drying are described, along with measurements of their dielectric constant. These compare favourably with data obtained from a simple formula for a mixture of dielectric materials.