The objective of this research was to identify reliable methods based on the thermal stress tolerance of cucumber seeds, which would be efficient for evaluating their physiological potential. The study was conducted in three experimental phases using seed lots of Safira and Joia cultivars and included procedures for the assessment of seed physiological potential from germination, field emergence, controlled deterioration and accelerated ageing tests. Results indicated that the controlled deterioration (24% water content/ 48 h / 45 ºC), and the traditional and saturated salt accelerated ageing (41 ºC for 96 h) tests are sensitive to differences in the physiological quality of cucumber seed lots.