The properties of metal hydride materials will be significantly degenerated by the poisoning effect of impurity gases such as CO, O2, H2S, etc. However, there are few reports on the poisoning kinetic model of metal hydride, which is important for the high-purity hydrogen purification and production from industry H2-contained waste gas. Hence, in this work, a novel poisoning hydrogen absorption kinetic model for metal hydride running in the CO + H2 mixture gas is developed, which considers the effect of poisoning on the volume growth rate of the product phase based on classical Johnson-Mehl-Avrami model. The novel model is also validated by comparison with experimental data of hydrogen absorption of LaNi4.3Al0.7 in a hydrogen atmosphere containing CO (∼0.1% v/v). The comparison results showed good agreement between model and experiment in the temperature range of 323–403 K. Based on experimental data and model, the reaction mechanism and rate-controlling steps of LaNi4.3Al0.7 hydrogenation process with 0.1%v/v CO were further uncovered. Display omitted •A novel poisoning hydrogen absorption kinetic model is developed and validated.•The poisoning factor related to the temperature is introduced into the kinetic model.•The effect of impurities becomes weakened with the rise of temperature.•Hydrogenation rate-controlling step under CO + H2 depends on surface CO absorption/desorption.