Abstract: The kinetics of reaction of lithium deuteride powder with O_2, CO_2 and water vapor is (studied.) The experimental results show that lithium deuteride reacts with O_2 and CO_2 at very small (reaction) rate but with water vapor at comparatively larger rate at room temperature (≈28 ℃). The reaction process with water vapor could be described using the unreacted shrinking core model. The second-order kinetics is appropriate for the chemical reaction on the surface of lithium deuteride and reaction rate constant is 0.281 kPa~(-1)·min~(-1).