Abstract: The effect of plant growth regulators. Indole acetic acid (1AA), Abscisic acid (ABA) and Kinetin each at 10 -6M were used as seed soaking treatment on Glycine max (L.) NARC 1. Plants were subjected to 3h temperature shock at 42 °C continued for a period of 10 days. The plants were harvested 46 days after sowing and analyzed for 1AA oxidase activity and for endogenous level of ABA. IAA oxidase activity of roots from temperature shocked plants were found significantly lower than that of control. The maximum values were recorded in IAA and kinetin treated plants and the minimum value was recorded in ABA treated plants. Whereas, the plants maintained without temperature shock was found significantly higher than that of control. The maximum values were recorded in IAA and ABA treated plants as compared to kinetin. The temperature shocked plants increased the endogenous level of ABA as compared to without heat shocked. This increase in the endogenous ABA level in the leaves might be the result of de novo synthesis of ABA in response to increase in temperature.