Ammonium nitrate can be withheld from the Bachmann reaction at 35°C. for several hours without reducing the yield of RDX below approximately 50% of the normal value for the given amount of ammonium nitrate added. The rates of formation of RDX, on the addition of ammonium nitrate from 15 min. to five hours after the reaction has started in its absence, are approximately the same and are approximately one-half that when ammonium nitrate is present initially. A low temperature analysis for hexamine in the Bachmann mixture, by precipitating hexamine as the styphnate, indicates that hexamine disappears from the reaction mixture within five seconds at 35°C, either in the presence or absence of ammonium nitrate.