The borohydrides, because of their unique chemical properties, have become compounds of considerable interest, both theoretical and practical. Among the practical applications is the use of sodium borohydride for the generation of hydrogen under conditions in which it is important to obtain the largest possible volume from the smallest weight and volume of generating material and apparatus. This application is discussed in detail later in this paper; the use of the alkali metal borohydrides as reducing agents in organic and in analytical chemistry will be described elsewhere.