Glycinebetaine, an osmoprotectant, is known to provide protection against most of the abiotic stresses. High temperatures during flowering decrease seed production in many crop plants. An experiment was conducted in a pot-culture with several soybean genotypes under optimum water and nutrient conditions. The glycinebetaine treatments included were control: plants received no glycinebetaine spray; glycinebetaine treatment in vivo: plants received glycine betaine at 2 kg/ha as a foliar spray before flowering; glycinebetaine treatment in vitro: pollen collected from flowers of control were germinated on a pollen germination medium supplemented by glycinebetaine. The temperature treatments consisted of 15 oC to 45 oC at 5 oC intervals. Cardinal temperatures at each treatment were calculated for all the genotypes. The results showed that when averaged over all the genotypes and all the temperatures, pollen germination was found 15 and 21% more under in vivo and in vitro glycine betaine treatments, respectively when compared to the control. Genotypes were classified based on a total response index developed based on their total response to glycinebetaine at both in vivo and in vitro conditions. The factors included to calculate the response index were maximum pollen germination, and cardinal temperatures (Tmax, Tmin and Topt). The genotypes were classified as extremely-responsive (Hutcheson, D 68-0102 and Stressland), more-responsive (DP 4690RR, DK 3964RR, Williams 82 and Stalwart III), less-responsive (P 9594, Maverick and DARE), and not-responsive (DG 5630RR). The results show that soybean genotypes vary in their response to temperature and the temperature response was modified by both in vivo and in vitro application of glycinebetaine. We conclude that glycinebetane may provide protection against extreme temperature conditions and manipulation of biosynthetic pathway of glycinebetaine into soybean may be useful under stressful environments.