
Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical rocket, or from an external source, as with ion engines.

Aluminium is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating.

Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting many compounds such as boric acid, the mineral borax, and the ultra-hard crystal boron carbide.

Decaborane, also called decaborane(14), is the borane with the chemical formula B10H14. This white crystalline compound is one of the principal boron hydride clusters, both as a reference structure and as a precursor to other boron hydrides. It is toxic and volatile, with a foul smelling odor.

Diborane(6), generally known as diborane, is the chemical compound consisting of boron and hydrogen with the formula B2H6. It is a colorless, pyrophoric gas with a repulsively sweet odor. Synonyms include boroethane, boron hydride, and diboron hexahydride. Diborane is a key boron compound with a variety of applications. It has attracted wide attention for its electronic structure. Its derivatives are useful reagents.

Diethylenetriamine (abbreviated Dien or DETA) and also known as 2,2’-Iminodi(ethylamine)) is an organic compound with the formula HN(CH2CH2NH2)2. This colourless hygroscopic liquid is soluble in water and polar organic solvents, but not simple hydrocarbons. Diethylenetriamine is structural analogue of diethylene glycol. Its chemical properties resemble those for ethylene diamine, and it has similar uses. It is a weak base and its aqueous solution is alkaline. DETA is a byproduct of the production of ethylenediamine from ethylene dichloride.

2-Dimethylaminoethylazide (DMAZ) is a liquid fuel being investigated for use as a spacecraft propellent to replace the toxic, carcinogenic monomethylhydrazine. It is a member of the competitive impulse non-carcinogenic hypergol (CINCH) family which were assessed as a replacement for hydrazine-derived propellants. DMAZ was also found to be sensitive to impact, direct flame, shock wave, heat in confined space, and electrostatic discharge.

Furfuryl alcohol is an organic compound containing a furan substituted with a hydroxymethyl group. It is a colorless liquid, but aged samples appear amber. It possesses a faint odor of burning and a bitter taste. It is miscible with but unstable in water. It is soluble in common organic solvents.

The Green Propellant Infusion Mission (GPIM) was a NASA technology demonstrator project that tested a less toxic and higher performance/efficiency chemical propellant for next-generation launch vehicles and CubeSat spacecraft. When compared to the present high-thrust and high-performance industry standard for orbital maneuvering systems, which for decades, have exclusively been reliant upon toxic hydrazine based propellant formulations, the "greener" hydroxylammonium nitrate (HAN) monopropellant offers many advantages for future satellites, including longer mission durations, additional maneuverability, increased payload space and simplified launch processing. The GPIM was managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, and was part of NASA's Technology Demonstration Mission Program within the Space Technology Mission Directorate.

Guanidine nitrate is the chemical compound with the formula [C(NH2)3]NO3. It is a colorless, water-soluble salt. It is produced on a large scale and finds use as precursor for nitroguanidine, fuel in pyrotechnics and gas generators. Its correct name is guanidinium nitrate, but the colloquial term guanidine nitrate is widely used.

Gunpowder, also known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur (S), carbon (C), and potassium nitrate (saltpeter, KNO3). The sulfur and carbon (in the form of charcoal) act as fuels while the saltpeter is an oxidizer. Gunpowder has been widely used as a propellant in firearms, artillery, rocketry, and pyrotechnics, including use as a blasting agent for explosives in quarrying, mining, and road building.

Hexanitrohexaazaisowurtzitane, also called HNIW and CL-20, is a nitroamine explosive with the formula C6H6N12O12. The structure of CL-20 was first proposed in 1979 by Dalian Institute of Chemical Physics. In the 1980s, CL-20 was developed by the China Lake facility, primarily to be used in propellants. It has a better oxidizer-to-fuel ratio than conventional HMX or RDX. It releases 20% more energy than traditional HMX-based propellants, and is widely superior to conventional high-energy propellants and explosives.

Hydrazine is an inorganic compound with the chemical formula N2H4. It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour.

Hydrazinium nitroformate (HNF) is a salt of hydrazine and nitroform (trinitromethane). It has the molecular formula [H2NNH3]+[C(NO2)3]− and is soluble in most solvents.

Hydroxylamine is an inorganic compound with the formula NH2OH. The pure material is a white, unstable crystalline, hygroscopic compound. However, hydroxylamine is almost always provided and used as an aqueous solution. It is used to prepare oximes, an important functional group. It is also an intermediate in biological nitrification. In biological nitrification, the oxidation of NH3 to hydroxylamine is mediated by the enzyme ammonia monooxygenase (AMO). Hydroxylamine oxidoreductase (HAO) further oxidizes hydroxylamine to nitrite.

Hydroxylammonium nitrate or hydroxylamine nitrate (HAN) is an inorganic compound with the chemical formula [NH3OH][NO3]. It is a salt derived from hydroxylamine and nitric acid. In its pure form, it is a colourless hygroscopic solid. It has potential to be used as a rocket propellant either as a solution in monopropellants or bipropellants. Hydroxylammonium nitrate (HAN) based propellants are a viable and effective solution for future green propellant based missions, as it offers 50% higher performance for a given propellant tank compared to commercially used hydrazine.

A hypergolic propellant combination used in a rocket engine is one whose components spontaneously ignite when they come into contact with each other.

Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.

Nitroethane is an organic compound having the chemical formula C2H5NO2. Similar in many regards to nitromethane, nitroethane is an oily liquid at standard temperature and pressure. Pure nitroethane is colorless and has a fruity odor.

Pentaborane(9) is an inorganic compound with the formula B5H9. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fuel. Like many of the smaller boron hydrides, pentaborane is colourless, diamagnetic, and volatile. It is related to pentaborane(11) (B5H11).

Project Morpheus was a NASA project that began in 2010 to develop a vertical takeoff and vertical landing (VTVL) test vehicle called the Morpheus Lander. It is intended to demonstrate a new nontoxic spacecraft propellant system and an autonomous landing and hazard detection technology. The prototype planetary lander is capable of autonomous flight, including vertical takeoff and landings. The vehicles are NASA-designed robotic landers that will be able to land and take off with 1,100 pounds (500 kg) of cargo on the Moon. The prospect is an engine that runs reliably on propellants that are not only cheaper and safer here on Earth, but could also be potentially manufactured on the Moon and Mars.

Propyne (methylacetylene) is an alkyne with the chemical formula CH3C≡CH. It is a component of MAPD gas—along with its isomer propadiene (allene), which was commonly used in gas welding. Unlike acetylene, propyne can be safely condensed.

RP-1 (alternatively, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. RP-1 provides a lower specific impulse than liquid hydrogen (LH2), but is cheaper, is stable at room temperature, and presents a lower explosion hazard. RP-1 is far denser than LH2, giving it a higher energy density (though its specific energy is lower). RP-1 also has a fraction of the toxicity and carcinogenic hazards of hydrazine, another room-temperature liquid fuel.

Syntin is a hydrocarbon with the molecular formula C10H16 used as a rocket fuel. It is a mixture of four stereoisomers (see below). It has a density of 0.851 g/mL, and a boiling point of 158 °C. Due to the presence of three strained cyclopropane rings, the molecule has a highly positive enthalpy of formation: ΔfH°(l)= 133 kJ/mol (980 kJ/kg, the average value for the isomeric mixture), bringing additional energy into the combustion process. It has advantages over the traditional hydrocarbon fuels, such as RP-1, due to higher density, lower viscosity and higher specific heat of oxidation.

Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name it has the formula Al2(C2H5)6 (abbreviated as Al2Et6 or TEA), as it exists as a dimer. This colorless liquid is pyrophoric. It is an industrially important compound, closely related to trimethylaluminium.