Four new antihypertensive thiomorpholinylmethylphenol compounds were synthesized by its potential antihypertensive and antiarhythmic properties. The pK(a) values were determined experimentally, with die aid of program SQUAD, by Capillary Zone Electrophoresis (CZE) (T = 310.15 K and / = 0.05 mol.dm(-3)) and by UV spectrophotometry at pseudophysiological conditions (T = 310.15 K and / = 0.15 mol.dm(-3)). obtaining good agreement between the values determined with both techniques. A theoretical study was followed to propose a deprotonation mechanism for each compound. The log P values were also determined between n-octanol and water and compared with the values of other similar compounds to relate it with its possible biological activity.