We study the kinetics of hydrogen sorption in Mg‐Ti‐H nanoparticles prepared by gas phase condensation of mixed Mg‐Ti vapors under a H2‐containing atmosphere. Four samples with different Ti contents from 14 to 63 at.% Ti are examined in the 100–150 °C range. The hydrogen absorption kinetics coupled with the formation of MgH2 can be described by a nucleation and growth model. The activation energy is in the range  kJ/mol and the rate constant (at 150 °C) increases from s−1 to s−1 with increasing Ti content. Hydrogen desorption is well modeled by a sequence of surface‐limited and contracting‐volume kinetics, except at the highest Ti content where nucleation and growth is observed. The activation energy of surface‐limited kinetics is /mol. The rate constant (at 150 °C) increases from s−1 to  s−1 with the Ti content. These results open an unexplored kinetic window for Mg‐based reversible …