Hydroxylammonium perchlorate

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Hydroxylammonium perchlorate
IUPAC name
Hydroxylammonium perchlorate
Other names
Hydroxylamine perchlorate
Molar mass 133.49 g/mol
Appearance White hygroscopic solid
Odor Odorless
Density 2.06 g/cm3[1]
Melting point 85–89 °C (185–192 °F; 358–362 K) [4][5]
Boiling point Decomposes, explodes
Solubility Soluble in diethyl ether, ethanol, methanol
Solubility in diethyl ether 30.4 %w/w[2]
Solubility in ethanol 71.2 % w/w[3]
-278.236 kJ/mol
Related compounds
Related compounds
Hydroxylammonium chloride
Hydroxylammonium nitrate
Hydroxylammonium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Hydroxylammonium perchlorate (H3NOHClO4) or HAP is the perchloric acid salt of hydroxylamine. It is a powerful explosive and rocket propellant, but its use is limited due to its hygroscopicity and cost.



Hydroxylammonium perchlorate decomposes when heated above 89 °C, releasing nitrogen, nitrous oxide, oxygen, chlorine, HCl, water vapors. It can even explode if heated too high.

Woelen described the decomposition flame as blue.[6] Also, adding sodium bromate (NaBrO3) to a concentrated solution of hydroxylammonium perchlorate will cause an explosion after addition. If potassium bromate is used instead, there is a delay, then the mixture ignites in a very violent reaction. A similar reaction occurs if iodite or chlorite salts are used.[7]


Hydroxylammonium perchlorate is a hygroscopic white solid, very soluble in water. At 18 % relative humidity, crystalline HAP absorbs enough moisture from air to nearly dissolve itself, within 10 minutes.[8]


Hydroxylammonium perchlorate is explosive, though its sensitivity is limited by its hygrocopicity. Addition of bromates, iodates or chlorites will cause ignition or even detonation. When heated above 89 °C, it will begin to decompose violently, and at 150 °C it will explode.[9] Its sensitivity has been described to be similar to that of ETN.[10]


Hydroxylammonium perchlorate is not sold due to its hazards and has to be prepared in situ.


Hydroxylammonium perchlorate can be prepared by reacting hydroxylammonium chloride with barium perchlorate, in absolute ethanol:[11]

Ba(ClO4)2 + H3NOHCl → 2 H3NOHClO4 + BaCl2

Hydroxylammonium sulfate can also be used, though a different solvent than ethanol may be required.

Ba(ClO4)2 + (H3NOH)2SO4 → 2 H3NOHClO4 + BaSO4




Hydroxylammonium perchlorate is a powerful oxidizer and may even explode if heated at high temperatures.

Hydroxylamine and its compounds are irritant to the respiratory tract, skin, eyes, and other mucous membranes and are considered possible mutagenic.


Hydroxylammonium perchlorate is very hygroscopic and should only be kept in airtight bottles, and only for short periods of time.


Hydroxylammonium perchlorate should first be converted to hydroxylammonium chloride or sulfate, which can be done by diluting the compound, then adding a potassium salt (or KOH). The resulting hydroxylamine salt solution is filtered off and neutralized like any other hydroxylamine salt. It can be neutralized by using a ketone and then gently heating the resulting oxime, which reforms the ketone and releases nitrogen gas and water. It can also be neutralized by diluting it with water and carefully adding ferric salts or other compounds known to accelerate its decomposition.

Reduction of hydroxylamine with Zn/HCl yields ammonia.


  1. https://www.docdroid.net/vugHRJ9/atlantic-research-corporation-research-on-the-deflagration-of-high-energy-solid-oxidizers.pdf
  2. Grigorovich, Z. I.; Lyubimova, G. N.; Razumova, A. P.; Russian Journal of Inorganic Chemistry (Translation of Zhurnal Neorganicheskoi Khimii); vol. 25; (1980); p. 543 - 546; Zhurnal Neorganicheskoi Khimii; vol. 25; (1980); p. 975 - 981
  3. Grigorovich, Z. I.; Lyubimova, G. N.; Razumova, A. P.; Russian Journal of Inorganic Chemistry (Translation of Zhurnal Neorganicheskoi Khimii); vol. 25; (1980); p. 543 - 546; Zhurnal Neorganicheskoi Khimii; vol. 25; (1980); p. 975 - 981
  4. https://www.docdroid.net/vugHRJ9/atlantic-research-corporation-research-on-the-deflagration-of-high-energy-solid-oxidizers.pdf
  5. Makhonina; Lempert; Nechiporenko; Russian Journal of Inorganic Chemistry; vol. 44; nb. 2; (1999); p. 167 - 170
  6. https://www.sciencemadness.org/whisper/viewthread.php?tid=13174#pid180372
  7. https://www.sciencemadness.org/whisper/viewthread.php?tid=26982#pid305423
  8. https://www.docdroid.net/vugHRJ9/atlantic-research-corporation-research-on-the-deflagration-of-high-energy-solid-oxidizers.pdf
  9. Lidin R.A., Andreeva L.L., Molochko V.A. Inorganic matter constants (Константы неорганических веществ) - M.: Bustard, 2006, pp. 135
  10. https://www.docdroid.net/vugHRJ9/atlantic-research-corporation-research-on-the-deflagration-of-high-energy-solid-oxidizers.pdf
  11. https://patents.google.com/patent/US2768874

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