Natural zeolites and synthetic high surface area metal oxides have been investigated as adsorbents for solar-powered refrigeration systems as well as off-peak thermal storage devices. In this laboratory we have used a Du Pont 1090 thermal analyzer to determine both adsorptive capacity and adsorption isobars with water as the heat transfer agent. For one sample methanol was also investigated. Based on the shape of the isobars, performance of adsorbents as part of cooling or heating systems can be predicted. A natural zeolite was compared with two alumina and a porous carbon sample at different dew points and temperatures between ambient and 200° C. The instrumental arrangement included a constant temperature bath and a thermogravimetric analyzer modified to allow the use of water vapor saturated gases.