A process for the conversion of boric acid to dry boron oxide by thermal decomposition is described. Boron oxide may be produced as a powder or in the form of pellets, and in either form may additionally be enclosed in a gas permeable container to control particulate contamination. Applications are further disclosed for the use of boron oxide formed by this process to remove water from evacuated chambers and from gases. Specific applications include removing water from both inert gases and reactive gases, especially halogen and halogenated gases. Further applications directed to optical amplifiers and gas purifiers are also discussed.