We present the analysis of hydrogen absorption kinetics of MmNi(4.7)Al(0.3) samples performed to identify the limiting process during the reaction. Measurements using the Sieverts technique on activated (powdered), surface-treated (Pd-covered)and intentionally oxided samples were compared to the pressure-time dependence proposed in recently published models. While intentionally-oxided samples showed a hydrogen absorption kinetics limited by surface-related processes (chemisorption and/or surface barrier), the reaction with hydrogen in untreated or surface-improved samples were dominated by hydrogen diffusion. As we show in this work, the use of the proposed expressions to fit absorption experimental data provides a simple and useful method to identify the slowest individual process.