Developing a safe hydrogen carrier without the risks of high pressures and toxicities is an issue of significant urgency. In this study, we prepared a polymeric hydrogen carrier with high thermal stability by incorporating 2-propanol and acetone units into polymers. Poly(methyl vinyl ketone) with a high molecular weight (~105) was synthesized via bulk polymerization of methyl vinyl ketone and then dehydrogenated in one step to give poly(3-buten-2-ol) in high yield. Reversible hydrogen fixation and release by these polymers were achieved with full conversion under mild conditions (80–180 °C, ≦3 atm hydrogen pressure). A simple temperature-dependent hydrogenation/dehydrogenation cycle that operated at temperatures higher than the boiling points of 2-propanol and acetone in the presence of an iridium complex catalyst was established by virtue of having these groups as pendants of the vinyl chain, with a compact repeating unit to maximize the mass hydrogen storage density of 2.8 wt%. Polymeric hydrogen carrier with high thermal stability was prepared by incorporating isopropanol and acetone units into polymers via a facile reaction process. Reversible hydrogen fixing and releasing were achieved with full conversion under mild conditions. Temperature-dependent facile hydrogenation and dehydrogenation cycle that operated at temperatures higher than the boiling points of isopropanol and acetone, in the presence of an iridium complex catalyst, was established by virtue of having these groups as pendants of the vinyl chain, with a compact repeating unit to maximize the mass hydrogen storage density of 2.8 wt%.