The modifications caused in the respiration, metabolic enzyme activity and physiological quality of rice seeds under different temperatures was analyzed, and the relationship between these parameters used as an indication of the deterioration process of seeds. Seeds were exposed during 24h and submitted to tests for germination, first count germination, index the germination speed, length and dry weight of shoot and roots, electrical conductivity, and respiratory and enzymatic activity. The experiment was completely randomized with four replicates and the averages compared by Tukey test (p <= 0.05) with subsequent regression analysis. Rice seeds showed a decrease in germination and vigor in temperatures above 25 degrees C. The activity of malate dehydrogenase enzyme increased in the plants whose seeds were exposed to 15 and 35 degrees C (ranging from 32.55 to 39.04 mu mol NAD(+)/g/ MF/min, respectively), while the enzyme glucose-6-phosphate dehydrogenase increased with no significant differences when seeds were subjected to 15, 30 and 35 degrees C (0.58, 0.71 and 0.74 mu mol NADPH/g MF/min, respectively). It can be concluded that the evaluated biochemical tests can be used to identify the deteriorating process of rice seeds and that temperatures above 25 degrees C can deteriorate the quality of rice seeds var. Pelota.3815459