NEW MATERIAL:A betaine compound expressed by formula I [R1 is straight- chain or branched-chain 8-22C alkyl, alkenyl or hydroxyalkyl; X is H or hydroxyl; R2 to R4 are 1-4C alkyl; Y is -CH2CH(OH)CH2SO3 or -(CH2)2-5SO3; n is 0 or 1-5; when n is 1, X is H or hydroxyl and when n is 0, 2 or 3, X is H].

EXAMPLE: N-Dodecyl-N-(3-trimethylammonio-2-hydroxypropylene)amino-2- hydroxypropylenesulfonate.

USE: The betaine compound expressed by formula I has mild action to skin and has excellent foaming force and cleaning force and is useful as a surfactant for cleaning hair or body.

PREPARATION: An aliphatic primary amine expressed by formula II is reacted with a compound expressed by formula III (Z is halogen; A is OH, halogen, etc.) and the resultant product is reacted with a metal salt of compound expressed by formula IV (M is alkali metal) to obtain the compound expressed by formula I.