The present invention relates to new histamine H
3
(H
3
) 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 H
3
receptors. The invention also cover the combinations of a compound of the general formula (I) and an acetylcholinesterase inhibitor.