10.22376/ijpbs.2019.10.1.p1-12 Volume 1 Issue 2 2010 (April - June) Conductance measurements of ion-pair association of acetylcholine and s- acetylthiocholine bromides in aqueous and non-aqueous solvents at 25°C were found to depend on the association of the cation and increased with increasing cation crystallographic radius. Solvation of cation increased with increasing cationic size in aqueous and non-aqueous solvents.The association constant KA was analyzed on the basis of solvent separated- ion pair model. lessThan br / greaterThan Nasr H. El-Hammamy,Aida I. Kawana,Moustafa M. El-Kholy Acetylcholine, S-Acetylthiocholine bromides, cation solvation in aqueous and non-aqueous solvents. -