The present invention relates to new histamine-3 (H3) receptor subtype preferring ligands of formula (I) (as defined in the claims) and/or geometric isomers and/or stereoisomers and/or diastereoisomers and/or salts and/or hydrates and/or solvates thereof. The invention further relates to pharmaceutical compositions comprising such compounds and the use of these compounds in methods for treating or preventing of conditions which require modulation of histamine-3 (H3) receptors. The invention also provides a method for manufacturing medicaments useful in the treatment or prevention of such conditions.˙