The present invention relates to new histamine H3 (H3) receptor subtype selective ligands of the general formula (I) and/or geometric isomers and/or stereoisomers and/or diastereomers and/or salts and/or hydrates and/or solvates thereof. The invention further relates to pharmaceutical compositions containing such compounds and the use of these compounds as medicaments for treatment and/or prevention of conditions which require modulation of H3 receptors. The invention also cover the combinations of a compound of the general formula (I) and an acetylcholinesterase inhibitor.