The adsorption of H2 molecule and H atom was investigated to predict the activity of the Chini clusters in the H2 generation. The results are shown in Table and Figure in SI. The computed geometries of the adducts revealed specific sites on the clusters where hydrogen atoms prefer to bind. For the H atoms we observe them bound to a single Pt centre. The Pt-H distance ranges from 1.603 to 1.648 Å, consistent with the known values for Pt-H complexes . The H atom is positioned symmetrically slightly moving to the centre of the triangle as the cluster increases, giving Pt-Pt-H angles that are similar in value, generally ca. 85-95°. The example of such a structure formed with [Pt3(CO)6]4 2-and the H atom is shown in Figure in the supplementary information file. Geometries of clusters bound with H atoms show slight distortions, particularly in the smaller clusters. When the cluster size increases, the presence of more Pt3 units helps to stabilize structures minimizing the impact of H on their deformations.