Heat treatment by superheated steam has been utilized in several industrial fields including sterilization, desiccation, and cooking. Saturated and superheated steam is used in a number of home appliances, such as humidifiers, steam cookers, and steam irons. In these applications, in order to save electricity, it is necessary to produce steam on demand. Therefore, quick start-up and cut-off responses are required. However, most electrically energized steam generators require a relatively long time to generate steam due to the large heat capacities of the water in the container. We proposed a new method using containing porous material to generate saturated or superheated steam quickly. Steam may be generated rapidly using containing porous material because the heat capacity of the water in the meniscus is extremely small. The main objective of the present work was to show the performance of rapid steam generator we proposed and experimentally investigate the effect of the effective thermal conductivity of the porous material on the rapid and efficient generation of saturated and superheated steam. As a result, in order to generate superheated steam quickly and efficiently, the generator should be constructed from lowthermal-conductivity material. The energy utilization efficiency was analyzed based on a simplified one-dimensional model of the heat and fluid flow in the porous material, the calculated results were shown to be in good agreement with the experimental results. Based on the proposed model for the energy utilization efficiency on steam generation, the proposed rapid superheated steam generator is suitable for miniaturization. (C) 2015 Elsevier Ltd. All rights reserved.