Manufacture of complex hydrides

The process for the manufacture of alkali metal aluminum tetrahydrides in solid, readily filterable form comprising pressure hydrogenating at a temperature of about 50.degree. C. to 250.degree. C., a mixture consisting essentially of aluminum, the hydride of an alkali metal, and an organic liquid reaction medium stable at reaction conditions, said medium being selected from the class consisting of aliphatic hydrocarbons and aromatic hydrocarbons, said pressure hydrogenating being carried out in the presence of a catalyst selected from the group consisting of alkyl compounds of metals of Group I-A, II-A and III-A of the periodic table, said catalyst being in proportions of up to about 5 weight percent of the reaction medium thereby forming an alkali metal aluminum tetrahydride consisting of aluminum, the alkali metal and hydrogen in solid form and recovering said solid.