Abstract: The present invention relates to physically and chemically stable salts of the selective histamine preceptor antagonist compound of 1-[4-(4-{3-[(2R)-2-methyl-pyrrolidin-1-yl]-propoxy}-phenoxy)-piperidin-1-yl]-ethanone of formula (1) and/or polymorphs thereof and/or hydrates/solvates thereof, the process for the preparation thereof, pharmaceutical compositions comprising them, and for use in the treatment and/or prevention of conditions requiring the modulation of histamine H3 receptors (e.g. Alzheimer's disease, obesity, schizophrenia, miochardial ischaemia, migraine, autism spectrum disorder).