Pulse radiolysis experiments were performed on hydrogenated, alkaline water at high temperatures and pressures to obtain rate constants for the reaction of hydrated electrons with hydrogen atoms (H• + eaq- → H2 + OH-, reaction 1) and the bimolecular reaction of two hydrated electrons (eaq- + eaq- → H2 + 2 OH-, reaction 2). Values for the reaction 1 rate constant, k1, were obtained from 100 - 325 oC, and those for the reaction 2 rate constant, k2, were obtained from 100 - 250 oC, both in increments of 25 C. Both k1 and k2 show non-Arrhenius behavior over the entire temperature range studied. k1 shows a rapid increase with increasing temperature, where k1 = 9.3 × 1010 M-1 s-1 at 100 oC and 1.2 × 1012 M-1 s-1 at 325 oC. This behavior is interpreted in terms of a long-range electron-transfer model, and we conclude that eaq- diffusion has a very high activation energy above 150 oC. The behavior of k2 is similar to that previously reported, reaching a maximum value of 5.9 × 1010 M-1 s-1 at 150 oC in the presence of 1.5 × 10-3 m hydroxide. At higher temperatures, the value of k2 decreases rapidly and above 250 oC is too small to measure reliably. We suggest that reaction 2 is a two-step reaction, where the first step is a proton transfer stimulated by the proximity of two hydrated electrons, followed immediately by reaction 1.