The dehydrogenation properties of Mg(BH4)(2) with various additives (SiO2, VCl3, CoCl2 and NbF5) were investigated. The addition of NbF5 significantly improved the extent of hydrogen release as well as the kinetics. While neat Mg(BH4)(2) starts to release hydrogen >270 degrees C, Mg(BH4)(2) with NbF5 begins hydrogen release similar to 75 degrees C, as confirmed by mass spectrometry and thermogravimetry. The maximum hydrogen yield of Mg(BH4)(2), obtained in the presence of 15 wt% NbF5, was 3.7, 7.4, 10.0, 11.4 wt% for 150, 250, 300 and 350 degrees C, respectively. Using pXRD, we confirmed that the final crystalline product at 300 degrees C from Mg(BH4)(2) + 15 wt% NbF5 was Mg, while it was MgH2 for neat Mg(BH4)(2). Solid state 11(B) NMR analysis of Mg(BH4)(2) with 15 wt% NbF5 at 300 degrees C showed significant selectivity toward the formation of Mg(B12H12) as intermediate, while neat Mg(BH4)(2) showed beta-Mg(BH4)(2), Mg(B2H6) as well as some Mg(B12H12). Our results demonstrate that NbF5 is a promising additive to provide high hydrogen yield values from Mg(BH4)(2) at moderate temperatures <300 degrees C. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.