The present invention relates to the use of one or more particular pyridinium salts for the treatment of keratin substances, particularly human keratin fibres such as hair. The invention also relates to a method for the treatment of keratin substances using said salts and optionally one or more chemical oxidizing agents. The invention also relates to a composition for lightening keratin substances comprising one or more pyridinium salts as defined hereinafter and one or more chemical oxidizing agents. The present invention also relates to one or more particular pyridinium salts and also to compositions containing them, especially compositions comprising a physiologically acceptable medium.
