Abstract: To investigate the effects of elevated atmospheric CO₂ concentration and temperature on soil nitrogen mineralization capacity in the rhizosphere of corn and rice in Mollisols, and to compare the similarities and differences in the responses of nitrogen mineralization processes in dryland and paddy fields to elevated CO₂ concentration and temperature, this study used open-top chambers (OTC) to simulate elevated atmospheric CO₂ concentration and temperature conditions. Using normal atmospheric CO₂ concentration (≈ 425 μmol·mol⁻¹) and ambient temperature as the control (CK), three treatments were established: elevated CO₂ concentration (≈ 700 μmol·mol⁻¹) without temperature increase (EC); ambient CO₂ concentration with elevated temperature (2 ℃ ± 0.5 ℃ above the control) (ET); and simultaneous elevation of both CO₂ concentration and temperature (ECT). Rhizosphere soil samples were collected at the large trumpet stage of corn and the tillering stage of rice (stage S1), as well as at the maturity stage of both crops (stage S2). Laboratory incubation was employed to systematically monitor the changes in various soil nitrogen forms and net nitrogen mineralization rates during the two growth stages, and kinetic models were applied for fitting. Results demonstrated that the effects of EC, ET, and ECT on soil nitrogen transformation exhibited significant crop specificity and temporal variability. In the S1 stage, EC enhanced net ammonification and nitrogen mineralization rates in rice soil, ET increased ammonium and inorganic nitrogen content in rice soil, while ECT significantly promoted these processes in corn soil. In the S2 stage, all treatments suppressed net ammonification and nitrogen mineralization in rice soil, with the most pronounced inhibition under ECT. Further kinetic analysis revealed that ECT markedly altered mineralization parameters in rice soil, highlighting its high sensitivity to climatic changes. These findings provide critical data and theoretical support for predicting nitrogen supply potential in Mollisols and optimizing nitrogen management strategies for cereal crops under future climate scenarios.