The present invention relates to a cationic aminopyridine of general formula (I), acid-addition salts thereof and solvates thereof: in which: R1 is a linear or branched, saturated C1-C20 alkyl radical, substituted and/or interrupted with a cationic radical. The present invention is also directed towards a process for synthesizing this cationic aminopyridine, compositions, uses, hair dyeing processes and devices using this cationic aminopyridine.
