These amino group-containing mono- or dithiols are represented by formula (I). In order to prepare them, ethylene sulfide is reacted with at least one compound of formula (II), the average number of moles of ethylene sulfide added corresponding to the total m+n, and possibly the compound of formula (I) as obtained is further reacted with ethylene sulfide in order to increase the value of m+n. R1 stands for a straight or branched alkyl or alkenyl group having 10 to 30 carbon atoms; R2 stands for a straight or branched alkyl or alkenyl group having 10 to 30 carbon atoms, or a —(CH2—CH2—S)n—H group; m and n, which are identical or different, each represent 0 or an integer in the range of 1 to 10 and satisfy 1.6≦m+n≦20; R′2 stands for a hydrogen atom in which case R2 in formula (I) will represent —(CH2—CH2—S)n—H, or a straight or branched alkyl or alkenyl group having 10 to 30 carbon atoms, in which case it will remain unchanged in the compound of the formula (I).