In this study, batchwise absorption of CO2 in N-methyl pyrolidone (NMP) was experimentally performed at different conditions using pressure decay method, and as a result, the equilibrium data, Henry's law constants, and kinetic data were reported. It was shown that solubility and diffusivity are two important factors affecting the kinetic behaviour of the system. This absorption system was mathematically modelled using Fick's second law accompanied by a time-dependent boundary condition. Thus, the diffusion coefficients of CO2 in NMP were calculated under different operating conditions by means of the experimental kinetic data. Furthermore, the influence of temperature and pressure on the diffusion coefficient of CO2 in NMP was analysed.