A solid personal care composition comprising at least 60 wt % of one or more solid surfactants of which at least 10 wt % comprises one or more compounds of formula (I) wherein R1 represents a C4-36 substituted or unsubstituted hydrocarbyl group； each of R2, R3, R4 and R5 independently represents a hydrogen atom or a C1-4 alkyl group and wherein at least one of R2, R3, R4 and R5 is not hydrogen； and M+ represents a cation.
