The present invention relates to a cosmetic composition capable of temporarily modifying the colour of the hair, of the type containing: a cosmetically acceptable solvent which comprises at least one alcohol； at least one pigment chosen from metal oxides and hydroxides, in particular iron(II) oxides and hydroxides, iron(III) oxides and hydroxides, mixtures of at least two of said iron(II) or (III) oxides or hydroxides, in particular mixtures of at least two iron(II) and/or iron(III) oxides, mixture(s) of at least two iron(II) and/or iron(III) hydroxides, mixtures of at least one iron(II) or iron(III) oxide with at least one iron(II) or iron(III) hydroxide, and mixtures of at least one iron(II) or iron(III) oxide and/or at least one iron(II) or (III) hydroxide with titanium dioxide； and at least one polymer for fixing said pigment. According to the invention, said pigment is capable of giving the hair a natural colour and in particular of covering white hair and said composition is liquid. The present invention also relates to a process for temporarily dying the hair, with a view to giving it a natural colour, according to which a solution containing at least one pigment, one polymer fixing said pigment and one cosmetically acceptable solvent is sprayed onto said hair.La présente invention concerne une composition cosmétique apte à modifier temporairement la couleur des cheveux, du type contenant: un solvant acceptable en cosmétique et qui comprend au moins un alcool, au moins un pigment choisi parmi les oxydes et hydroxydes métalliques, en particulier les oxydes et hydroxydes de fer(II), les oxydes et hydroxydes de fer (III), les mélanges d'au moins deux desdits oxydes ou hydroxydes de fer (II) ou (III), en particulier, les mélanges d'au moins deux oxydes de fer(II) et/ou fer (III), les mélange(s) d'au moins deux hydroxydes de fer(II) et/ou de fer (III), les mélanges d'au moins un oxyde de fer(II) ou fer (III) avec au moins un hydroxyde de fer(II) ou fer(III), et le
