Alkyl or cycloalkyl thiocyanates and isothiocyanates in which the hydrocarbon group has at least 6 carbon atoms, are obtained by the action of an alkali metal salt of thiocyanic acid on an inorganic ester of a higher alcohol, or by the action of cyanogen halide on the metal salt of a mercaptan; the products are useful as insecticides and fungicides. The hydrocarbon radicle may contain a straight or branched chain, saturated or unsaturated. The preparation of lauryl thiocyanate by converting lauryl alcohol to the chloride and treating this with sodium thiocyanate in ethyl alcohol is described in an example. Other lauryl esters specified include the bromide, sulphates, and phosphate, and the reaction may be accelerated by the use of finely divided copper as a catalyst. The starting material may be a crude lauryl alcohol containing octyl, decyl, tetradecyl alcohols and other homologues, obtained by the hydrogenation of vegetable oils such as coconut oil, or the free fatty acids, and gives a mixed thiocyanate. Lauryl thiocyanate may also be obtained by treating lead lauryl mercaptide with cyanogen chloride. The following alcohols may also be converted into the corresponding thiocyanates :--2 - methylpentanol - 1, 4 - methylpentanol - 1, 2 : 4 - dimethylhexanol - 1, 2 : 6 - dimethylhexanol - 1, 2 : 6 - dimethyloctanol, 2:4:6-trimethyldecanol-1, 2:4:6:8-tetramethyldecanol-1, secondary dodecanol and nonyl, cetyl, stearyl, oleyl, carnaubyl and melissyl and other alcohols up to 24-carbon atoms. Octyl alcohol is obtained by the hydrogenation of carbon monoxide and the other alcohols by the method indicated for lauryl alcohol. The products may be employed as insecticides in conjunction with kerosene or mineral oil as diluents, with fillers such as diatomaceous earth, or preferably as aqueous emulsions. Specified emulsifying agents include sulphonated fish oil, lecithinbutyl alcohol, sulphonated abietene, soap, sodium oleate, sodium fish oil soaps, casein, calcium caseinate, sulphonated petroleum, alkyl naphthalene sulphonic acids sodium resinate, and amine salts of higher fatty acids. Other insecticides and fungicides which may be used in conjunction with the products include nicotine, pyrethrum, rotenon, mineral oil emulsions, fluorine compounds, arsenicals, lime sulphur and Bordeaux mixtures. A table showing the toxicity of various emulsions is given. The Specification as open to inspection under Sect. 91 refers also to the preparation of the higher alkyl selenocyanates and telurocyanates. This subject-matter does not appear in the Specification as accepted.ALSO:Higher alkyl or cycloalkyl thiocyanates and isothiocyanates in which the alkyl hydrocarbon group has at least 6 carbon atoms and may be straight chain or branched, saturated or unsaturated, are used as insecticides in conjunction with kerosene or mineral oil as diluents, with fillers such as diatomataceous earth, or preferably as aqueous emulsions, and also in conjunction with other insecticides and fungicides. Specified thiocyanates or isothiocyanates are those derived from 2-methylpentanol-1, 4-methylpentanol-1, 2 : 4- and 2 : 6-dimethylhexanol-1, 2 : 6-dimethyloctanol, 2 : 4 : 6-trimethyl- and 2 : 4: 6 : 8-tetramethyldecanol-1, sec. dodecanol, and octyl, nonyl, cetyl, stearyl, oleyl, carnaubyl, melissyl, lauryl and other alcohols up to 24 carbon atoms. Specified emulsifying agents include sulphonated fish oil, lecithin-butyl alcohol, sulphonated abietene, soap, sodium oleate, sodium fish oil soaps, casein, calcium caseinate, sulphonated petroleum, alkylnaphthalene sulphonic acids, sodium resinate, and amine salts of higher fatty acids. Other specified parasiticides to be used in conjunction with the above products include nicotine, pyrethrum, rotenon, mineral oil emulsions, fluorine compounds, arsenicals, lime sulphur, and Bordeaux mixtures. A table showing the toxicity of various emulsions is given. The Specification as open to inspection under Sect. 91 refers also to the use of higher alkyl seleno- and telluro-cyanates. This subject-matter does not appear in the Specification as accepted.