Abstract A small semi-underground warehouse was constructed by waterproofing and placing a 7.6 cm thick precast concrete tank 304.8 cm long by 152.4 cm wide by 152.4 cm deep in the ground with the top of the tank at ground level. Two courses of 20.3-cm concrete blocks were installed above the walls and the warehouse was covered with a sheet-metal gable roof having a 45-degree slope. The warehouse had a peanut storage capacity of approximately 10.2 m3. A fan located in the south gable changed the headspace air once every two minutes. Thermocouples and relative humidity sensors placed at various locations throughout the warehouse indicated temperatures and relative humidities at these locations. Free fatty acid and total carbonyl analyses indicated acceptable quality maintenance in the underground storage and compared well with peanuts in conventional storages. Temperatures were more uniform in the underground warehouse than in the conventional warehouse.