The present invention relates to a dyeing composition comprising one or more acid direct dyes of indigoid type of formula (I) in which n has the value 0, 1 or 2, R1 represents an —SO3M group where M represents a hydrogen atom, an ion resulting from an alkali metal, an ammonium group or an ion resulting from an organic amine, X and Y represent, independently of one another, >C═O, Z below or Z′ below, Formula (Z) n′ having the value 0, 1 or 2, Formula (Z′) n″ having the value 0, 1 or 2, with (*) representing the point of attachment of Z or Z′ to the remainder of the molecule; provided that at least one of the coefficients n, n′ or n″ is other than zero, and one or more organic compounds (II) exhibiting a value for the Hansen solubility parameter δH of between 5 and 16 MPa1/2 and with a molecular weight of less than 250 g/mol. It also relates to a dyeing method which consists in applying such a composition to keratinous fibres.