Thermal treatment presents great potential on the alternative control of seed pathogens. However, there are few studies on this technology and, particularly, on its effect on the performance of seeds, especially vegetable seeds. This research aimed to study the relation of thermal treatment to the physiological potential and health of tomato seeds, identifying effective combinations of temperature and exposure time by health and vigor tests. In experiment I, seeds from 2 lots of cultivar UC-82 were treated with hot water (52, 53, 54, 55 and 60 ºC for 30 and 60 min) and dried for 72 h. In addition to two controls (chemically treated seeds and non-treated seeds), all treatments were evaluated in two periods by health, germination and vigor tests. In experiment II, seeds treated with hot water at 55 ºC/30 min and 60 ºC/60 min, were dried for 12 h. These treatments, and the controls used in experiment I, were evaluated by health, germination and vigor tests. Based on the results, it was concluded that the treatment with hot water (55 ºC/30 min) is consistent option to control of fungi Rhyzopus sp., Aspergillus sp. and Cladosporium sp., without impairing the physiological potential of tomato seeds. The treatments 52 to 54 ºC for 30 or 60 min did not damage the physiological potential of tomato seeds. The treatments at 60 ºC for 30 or 60 min are effective to control fungi, but lethal to tomato seeds
