This paper presents a transient analytical model to study the application of a greenhouse with packed bed thermal storage to crop drying. The performance of an even shape greenhouse with a packed bed and crop dryer was evaluated for drying of onions. The model was solved to compute the air temperatures and various functional components of the drying systems for a day of the month of May for the climatic condition of Delhi (India). The parametric study involved the effect of length and breadth of greenhouse and mass flow rate of air on the temperatures of crop. The thin layer drying equation was used to study the drying rate and hourly reduction in moisture content in the crop trays. It has been observed that the crop moisture content and drying rate decreases with the drying time of the day. A greenhouse of 6 m length, 4 m breadth with a 0.278 kg s(-1) air mass flow rate with a 0.25 m height of packed bed could dry 2280 kg of onion from a moisture content of 6.14-0.21 kg water/kg of dry matter in a 24 h drying period. (c) 2004 Elsevier Ltd. All rights reserved.