Microporous-macroporous carbononaceous monolith-type materials, prepared through a hard template method using silica as exo-templating matrices, have been impregnated by an etheric solution of LiBH4 to prepare LiBH4@Carbon samples. It has been shown that the amorphous character of LiBH4 is largely favoured when developing the carbon microporosity (pores smaller than 2 nm) and that LiBH4 dehydrogenation is strongly enhanced at low temperatures. The onset temperature of dehydrogenation can be decreased to 200°C and hydrogen capacity reaching 4.0 wt.% is obtained at 300°C with the carbon having the largest microporous volume, whereas the hydrogen release for bulk LiBH4 is negligible at the same temperature. In addition to some irreversible reactions with carbon surface groups the explanation for such modification could lie in the LiBH4 destabilization through confinement to the nanoscale range and associated amorphization.