Methods of synthesizing ammonia borane are provided. The methods comprise reacting at least one amine borane with ammonia such that ammonia borane is produced. Ammonia borane has a chemical formula Of NH3—BH3 and provides a good source of storage hydrogen making it useful in a variety of applications including a potential hydrogen source for fuel cells. The methods can further comprise separating the ammonia borane from the other products of the reaction. Exemplary methods can produce ammonia borane having purity greater than about 90 percent. In further examples, the methods can produce ammonia borane having purity greater than about 95 percent or greater than about 99 percent.