2,11,20,29-Tetra-tert-butyl-2,3-naphthalocyanine (TTBNc) was used as an alternative host to support magnesium (Mg) nanoparticles. After deposition and decomposition of dibutylmagnesium on TTBNc, Mg nanoparticles of around 4 nm supported on TTBNc were observed by TEM. These TTBNc stabilized Mg nanoparticles were found to absorb hydrogen at 100 degrees C and release hydrogen from 75 degrees C. The Mg-TTBNc material showed good hydrogen cycling properties and structural stability. Kinetic measurements showed fast hydrogen absorption within 2 min at 150 C. The hydrogen desorption kinetics were slower at the same temperature but faster at 250 degrees C with 80% of the hydrogen desorbed within 1 h. Enthalpy and entropy for hydrogen uptake and release in Mg-TTBNc determined from PCT measurements were found to be of 52.7 +/- 4.9 kJ morl H-2 and 107.8 +/- 9.4 J K-1 Mol(-1) H-2, respectively. These values are much lower than those of bulk Mg. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.