Cationic 6-hydroxypyridine compounds (I) are new. Cationic 6-hydroxypyridine compounds of formula (I) and their acid addition salts or solvates are new. R : H, halo, 1-4C alkyl, carboxyl or 1-4C alkoxy carbonyl； either R1 : saturated, linear or branched 1-4C alkyl (substituted or interrupted by a cationic group), where the 1-4C alkyl is optionally interrupted with one or more oxygen atoms and/or one or more N-R2 groups and optionally substituted by OH, alkoxy or 1-4C hydroxyalkyl, or optionally saturated or aromatic 5-8 membered cationic heterocycle (optionally substituted by 1-10C alkyl, OH, alkoxy, 1-4C alkoxyamino, 1-4C alkylamino, 1-4C dialkylamino, thio, 1-4C alkylthio, carboxyl, 1-4C alkylcarbonyl, sulfonyl, amido or 1-4C hydroxyalkyl)； and R2 : H, linear or branched 1-4C alkyl, benzyl or acetyl； or R1+R2+N : optionally saturated 5-8 membered cationic heterocycle ring or non-cationic heterocycle ring (optionally substituted by 1-10C alkyl, OH, 1-4C alkoxy, amino, 1-4C alkylamino, carboxyl, 1-4C dialkylamino, thio, 1-4C alkylthio, 1-4C alkylcarbonyl, sulfonyl, amido or 1-4C hydroxyalkyl) (when Z1 is N-R2), where the 5-8-membered cationic heterocycle ring optionally contains one or more heteroatoms of N (preferred) or O； and Z1 : O or N-R2. Independent claims are included for: (1) the preparation of (I)； (2) a cosmetic composition comprising (I) in a medium； (3) dyeing keratin fibers comprising applying the composition to the fibers to develop the desired coloration in the presence of an oxidizing agent, where the oxidizing agent is applied before, simultaneously or after the application of the composition； and (4) a multi-compartment device comprising a first compartment containing the cosmetic composition and a second compartment containing the oxidizing agent. [Image].La présente invention concerne une 6-hydroxy-pyridine cationique de formule générale (I), ses sels d'addition avec un acide et ses solvates : dans laquelle : La présente invention vise encore un
