Abstract: The levels of high temperatures (35, 38 and 41°C in 7 day/night) used in this study and decreased or delayed the germination of maize, rice and sorghum seeds. Growth regulator pre-treatments (especially GA₃) decreased this inhibitive effect of the high temperature to a great extends at 35 and 38°C in maize and rice seeds. In generally, no significant differences were detected between the control and kinetin treatments in maize and rice at 41°C. GA₃ increased rapidity germination and stimulated seed germination at all using temperate treatments in species. The case of sorghum for rapidity and final seed germination, plant growth regulators were effective thermal treatments at 38°C and over temperature. The high temperature was shortened the elongation of radicle and coleoptile and prevented at 35, 38 and 41°C. GA₃ enormously maintained its stimulative effect observed on the coleoptile and radicle emergence and elongation except at 41°C in rice. KIN had the lower the elongation of radicle when averaged across the GA₃ and control at high temperature conditions in all species.