NOVELTY - Ionic liquid (I) comprises alkanoyl ammonium salts cation (II).    USE - (I) is useful as a solvent for a chemical or biochemical reaction, which is an enzyme-catalyzed reaction and an organic synthesis reaction (claimed). (I) is useful as reaction media for situations, where hydrogen bonding and protic environment is required, and for biological solutes such as enzymes. (I) is useful as solvent: for matrix in matrix-assisted laser desorption/ionization mass spectrometry, solvent extraction process (e.g. to remove desired components from an immiscible liquid or solid), vehicle in chromatography (e.g. gas chromatography), metal-containing species, lubricant, hydraulic fluid and biocide; and in catalysis, an environment containing an activated acid or a strong base, liquefaction, nuclear fuel reprocessing, fuel cells, electrochemical applications, optical (including optoelectronic) systems, pervaporation, drug delivery, adhesives and sensors. (I) is useful: to dissolve a cellulosic material; and as a medium for a hydrolase- or esterase-catalyzed reaction.    ADVANTAGE - (I) is capable of existing in liquid form at and below 40 degrees C, preferably at room temperature. (I) contains 5 mass% or less of water. (I) has a viscosity of less than 500 centipoises at 25 degrees C (all claimed). (I) provides polar, hydrogen bonding fluid environment in the absence of hydroxyl groups. (I) has low toxicity and can be colorless. (I) has an ability to dissolve a wide range of inorganic, organic, polymeric and biological materials, often to a very high concentration. (I) has a wide liquid range, allowing both high and low temperature processes to be carried out in the same solvent. (I) exhibit excellent electrical and thermal conductivity whilst being non-flammable and recyclable. (I) has high solvation capability.    DETAILED DESCRIPTION - Ionic liquid (I) comprises alkanoyl ammonium salts cation of formula (N+HR6R7R8) (II).    R6 = alkanolyl group; either    R7 = hydrocarbyl group; and    R8 = H or hydrocarbyl; or    NR7R8 = heterocyclic group.    An INDEPENDENT CLAIM is included for the preparation of (I), comprising: providing a nitrogen-containing compound of (NR6R7R8) (IV); and neutralizing the compound (IV) with an acid.