Salts of amidoamines of general formula R.CO.NR1.X.NR2R3, where R.CO represents the acyl radical of an aliphatic or alicyclic acid having at least seven carbon atoms in the molecule, X is a divalent aliphatic radical and R1, R2 and R3 each represent a hydrogen atom or hydrocarbon radical, and an acid of formula R4OSO3H or R4SO3H, where R4 represents a hydrocarbon radical of at least 6 C atoms, are prepared by known methods, e.g. mixing a stoichiometric quantity of acid with a solution of the amidoamine in petroleum spirit, or by metathesis of the amine hydrochloride or sulphate with the alkali metal salt of the acid in a solvent which facilitates the removal of the inorganic salt produced. The amidoamines may be prepared by reacting a polyamine of formula HNR1-X-NR2R3 with a carboxylic acid which may be saturated or unsaturated and may be substituted, e.g. by halogen, hydroxyl, amino or carboxyl groups, or a derivative thereof such as the acid halide, anhydride or ester. Suitable polyamines are alkylene diamines, e.g. ethylene diamine, 1 : 2-diaminoethane, 1 : 2- and 1 : 3-diaminopropane, 1 : 2-, 1 : 3- and 1 : 4-diamino butane, and diamino derivatives of higher alkanes, or the alkylene chain may be interrupted by heterogeneous linkages such as NH or NA, where A is an aliphatic radical, e.g. polyalkylene polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, dipropylene triamine, tripropylene tetramine, and higher polymers of simple alkylene diamines, N,N1-dimethyl ethylene diamine, N,N1-diethyl ethylene diamine and N-phenyl ethylene diamine. Suitable acids, from which the R.CO group is derived, are fatty acids containing from 7 to 22 carbon atoms, e.g. lauric, palmitic, stearic and oleic acids, and alicyclic acids such as naphthenic acids obtained from the refinement of higher petroleum fractions, e.g. kerosine, gas and lubricating oils. Acids of formula R4OSO3H and R4SO3H, where R4 is a hydrocarbon radical of at least six carbon atoms referred to are alkyl sulphuric acid esters which may be obtained by reacting olefins containing at least eight carbon atoms with sulphuric acid, and aromatic sulphonic acids preferably having at least one alkyl group of at least three carbon atoms attached to the nucleus such as propylene-tetramer-alkylated benzene sulphonic acid, hexadecyl toluene sulphonic acids, di-isopropyl naphthalene sulphonic acid and tertiarybutyl naphthalene sulphonic acid, sulphonic acids from technical white oils, oleum-treated petroleum fractions and sulphonated hydrocarbons, e.g. kerosene, in sulphur dioxide, furfural or phenol which may be further alkylated using olefines containing up to twenty carbon atoms. The preparation of "Kerex" sulphonates of various amino alkyl naphthenamides is described and a list of other salts of amidoamines is given. "Kerex" is a Registered Trade Mark.ALSO:A composition for combatting noxious organisms, e.g. insect and fungus pests, comprises salts of an amidoamine of general formula R.CO.NR1.X.N.R2R3 where R.CO represents the acyl radical of an aliphatic or alicyclic acid having at least seven carbon atoms in the molecule, X is a divalent aliphatic radical and R1, R2 and R3 each represent a hydrogen atom or hydrocarbon radical with an acid of formula R4OSO3H or R4SO3H wherein R4 represents a hydrocarbon radical of at least 6 carbon atoms and a surface-active agent and/or a carrier. The amidoamines may be prepared by reacting a polyamine or formula HNR1.X.NR2R3 with a carboxylic acid which may be saturated or unsaturated and may be substituted, e.g. by halogen, hydroxyl, amino or carboxyl groups, or a derivative thereof such as the acid anhydride, halide or ester. Suitable polyamines are the alkylene diamines, e.g. ethylene diamine, 1 : 2-diaminoethane, 1 : 2- and 1 : 3-diaminopropane, 1 : 2-, 1 : 3- and 1 : 4-diaminobutane, and diamino derivatives of higher alkanes, or the alkylene chain may be interrupted by hetergeneous linkages such as NH or NA where A is an aliphatic radical, e.g. polyalkylene polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, dipropylene triamine, tripropylene tetramine, and higher polymers of simple alkylene diamines, N,N1-dimethyl ethylene diamine, N,N1-diethyl ethylene diamine, and N-phenyl ethylene diamine. Suitable acids are fatty acids containing from 7 to 22 carbon atoms, e.g. lauric, palmitic, stearic and oleic acids, and alicyclic acids such as naphthenic acids obtained from the refinement of higher petroleum fractions, e.g. kerosine, gas and lubricating oils. Acids of formula R4OSO3H or R4SO3H where R4 is a hydrocarbon radical of at least six carbon atoms referred to are alkyl sulphuric acid esters which may be obtained by reacting olefins containing at least eight carbon atoms with sulphuric acid, and aromatic sulphonic acids preferably having at least one alkyl group of at least three carbon atoms attached to the nucleus such as propylene-tetramer-alkylated benzene sulphonic acid, hexadecyl toluene sulphonic acids, di-isopropyl-naphthalene sulphonic acid and tertiary butyl naphthalene sulphonic acid. Sulphonic acids from technical white oils, oleum-treated-petroleum fractions and sulphonated hydrocarbons e.g. kerosene, in sulphur dioxide, furfural or phenol, are also suitable and may be further alkylated using olefins containing up to twenty carbon atoms. The composition may take the form of a dust containing from 1 to 10 per cent amidoamine salt in a powdered solid carrier, e.g. chalk, talc, silica, carbon, clay, fullers earth, kieselguhr, and sulphur, or a wettable powder containing at least 10 per cent active ingredient and a dispersing agent such as an alkali metal salt of a sulphuric acid or sulphonic acid containing at least ten carbon atoms, e.g. sodium lauryl sulphate, "Teapol" (Registered Trade Mark). Sodium phosphate and suspending agents, e.g. sodium lignosulphonic acid, sodium cellulose glycollate may also be incorporated. From 10 to 50 per cent active ingredient may be contained in a solution, dispersion or suspension, suitable for dilution and use as a spray, in an organic solvent, e.g. methanol, ethanol, isopropanol, secondary butanol, cyclohexanol or pyridine, or in a petroleum spray oil boiling in the ranges 275 DEG to 575 DEG F. and 575 DEG and 1000 DEG F. and having an unsulphonatable residue of at least 75 per cent. Suitable emulsifiers are ionic or non-ionic, and may be condensation products of ethylene oxide with higher alcohols, alkyl phenols, fatty or naphthenic acids, or partial esters of polyvalent alcohols with fatty acids, e.g. sorbitan monooleate, and oil soluble mineral oil sulphonates. A list of salts of amidoamino is given.