Abstract: An internally cooling compact solid dehumidifier was built and studied experimentally. Silica gel as the desiccant was coated to all the surfaces of primary process airflow channels of the dehumidifier. Experiments on performance of the dehumidifier with and without secondary cooling airflow were carried out under both humid and less humid conditions. The experimental results show that this new type of solid dehumidifier has excellent performance with secondary cooling airflow under both conditions. At humid conditions, the outlet moisture content and temperature of the primary airflow with secondary cooling are both lower than that without secondary cooling. The dynamic water vapor adsorption ratio of the silica gel within the dehumidifier reaches 12.4% after 20 minutes that is higher than currently known performance of silica gel dehumidifier.